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Transcript
The Epidemiology of
Infectious Diseases
in Illinois, 2001
Rod R. Blagojevich
Governor
Eric E. Whitaker, M.D., M.P.H.
Director
The Epidemiology of Infectious Diseases in Illinois, 2001
TABLE OF CONTENTS
Reportable communicable diseases in Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2001 summary of selected Illinois infectious diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Acquired immune deficiency syndrome/Human immunodeficiency virus . . . . . . . . . . . . 6
Amebiasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Bioterrorism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Blastomycosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Botulism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Brucellosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Campylobacteriosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Central nervous system infections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Arboviral infections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Aseptic meningitis or encephalitis of known etiology, excluding arboviruses . . 37
Aseptic meningitis or encephalitis of unknown etiology . . . . . . . . . . . . . . . . . . 39
Haemophilus influenzae (invasive disease) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Listeriosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Neisseria meningitidis, Invasive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
S. pneumoniae, Invasive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Streptococcus, Invasive group B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Cryptosporidiosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Cyclosporiasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Ehrlichiosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Enteric Escherichia coli infections (including E. coli O157:H7) . . . . . . . . . . . . . . . . . . 62
Foodborne outbreaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Giardiasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Hemolytic uremic syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Hepatitis,viral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Hepatitis A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Hepatitis B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Hepatitis non-A non-B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Histoplasmosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Legionellosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Lyme disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Malaria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Measles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Mumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Pertussis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Rabies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Rabies, potential human exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Rocky Mountain spotted fever . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Rubella . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Salmonellosis (non typhoidal) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Sexually transmitted diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Chlamydia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Gonorrhea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Syphilis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Shigellosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Staphylococcus aureus, intermediate or high-level resistance . . . . . . . . . . . . . . . . . . . . 174
Streptococcus pyogenes, group A (invasive disease) . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Tetanus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Tick-borne diseases found in Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Toxic shock syndrome due to S. aureus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
Trichinosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
Tuberculosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Tularemia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Typhoid fever . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Varicella . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
Yersiniosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Other incidents occurring in 2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
Reported cases of infectious diseases in Illinois, 2001 . . . . . . . . . . . . . . . . . . . . . . . . . 199
Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
Reportable Communicable Diseases in Illinois
The following diseases must be reported to local health authorities in Illinois
CLASS 1(a)- The following diseases are reportable by telephone immediately (within three hours):
1.
Anthrax
5.
Smallpox
2.
Botulism, foodborne
6.
Tularemia
3.
Plague
7.
Any suspected bioterrorist threat or event
4.
Q-fever
CLASS 1(b)-The following diseases are reportable within 24 hours of diagnosis:
1.
Botulism, infant, wound and other
12.
Measles
2.
Cholera
13.
Pertussis
3.
Diarrhea of the newborn
14.
Poliomyelitis
4.
Diphtheria
15.
Rabies, human
5.
Foodborne or waterborne illness
16.
Rabies, potential human exposure
6.
Hemolytic uremic syndrome, post-diarrheal
17.
Typhoid fever
7.
Hepatitis A
18.
Typhus
8.
Any unusual case or cluster of cases that may
19.
Enteric Escherichia coli infections (E. coli
indicate a public health hazard
O157:H7 and other enterohemorrhagic E.
9.
Haemophilus influenzae, meningitis and other
coli, enterotoxigenic E. coli,
invasive disease
enteropathogenic E. coli)
10.
Neisseria meningitidis, meningitis and invasive
20.
Staphylococcus aureus infections with
disease
intermediate or high-level resistance
11.
Streptococcal infections, group A, invasive
to vancomycin
(Including toxic shock syndrome) and sequelae
to group A streptococcal infections (rheumatic
fever and acute glomerulonephritis)
(Continued on next page)
1
CLASS II-The following diseases shall be reported as soon as possible during normal business hours, but within
seven days (exceptions to the seven-day notification requirement are marked with an asterisk; see note below):
1.
AIDS
27.
Malaria
2.
Amebiasis
28.
Meningitis, aseptic (including arbovirus infection)
3.
Blastomycosis
29.
Mumps
4.
Brucellosis
30.
Ophthalmia neonatorum (gonococcal)*
5.
Campylobacteriosis
31.
Psittacosis
6.
Chanchroid*
32.
Reye’s syndrome
7.
Chickenpox
33.
Rocky Mountain spotted fever
8.
Chlamydia*
34.
Rubella, including congenital
9.
Cryptosporidiosis
35.
Salmonellosis (other than typhoid)
10.
Cyclosporiasis
36.
Shigellosis
11.
Ehrlichiosis, human granulocytic
37.
Staphylococcus aureus infection, toxic shock
12.
Ehrlichiosis, human monocytic
syndrome
13.
Encephalitis
38.
Staphylococcus aureus infections occurring in
14.
Giardiasis
infants under 28 days of age (within a health care
15.
Gonorrhea*
care institution or with onset after discharge)
16.
Hantavirus pulmonary syndrome
39.
Streptococcal infections, group B, invasive disease,
17.
Hepatitis B
of the newborn
18.
Hepatitis C
40.
Streptococcus pneumoniae, invasive disease
19.
Hepatitis, viral, other
(including antibiotic susceptibility test results)
20.
Histoplasmosis
41.
Syphilis*
21.
HIV infection1
42.
Tetanus
22.
Legionnaires’ disease
43.
Trichinosis
23.
Leprosy
44.
Tuberculosis
24.
Leptospirosis
45.
Yersiniosis
25.
Listeriosis
26.
Lyme disease
*Must be reported by mail or by telephone to the local health authority within five days
1
HIV is reported by patient code number, not by name.
The occurrence of any increase in incidence of disease of unknown or unusual etiology should be reported,
with major signs and symptoms listed.
When an epidemic of a disease dangerous to the public health occurs and present rules are not adequate for
its control or prevention, more stringent requirements shall be issued by the Illinois Department of Public Health.
2
2001 Summary of Selected Illinois Infectious Diseases
In Illinois, the communicable disease (CD) surveillance system relies on the passive
reporting of cases required by state law. Diseases are made reportable because regular and timely
information is necessary for prevention and control efforts. Lists of notifiable diseases are
regularly revised to include new pathogens and to delete those of declining importance. The
current list mandates reporting, within specific time frames, of certain diseases and of selected
positive laboratory tests. The effectiveness of the surveillance system relies heavily on the
cooperation and support of health care providers, laboratories and local health departments in
submitting information. In Illinois, regulations require reporting by physicians, nurses, nurse
aides, dentists, health care practitioners, laboratory personnel, school personnel, long-term care
personnel, day care personnel and university personnel. Notifiable disease data are submitted by
the Illinois Department of Public Health (IDPH) on a weekly basis to be included with national
data in the Morbidity and Mortality Weekly Report. CD rules also include laboratory reporting.
Some isolates are required to be forwarded to IDPH. For selected agents and situations, pulse
field gel electrophoresis may be performed to subtype isolates.
There are 52 diseases or conditions listed as nationally reportable to the U.S. Centers for
Disease Control and Prevention (CDC). The number reflects certain combinations; for example,
HIV and AIDS are combined under one category (human immunodeficiency virus/acquired
immune deficiency syndrome [HIV/AIDS]) as are invasive group A streptococcus (GAS) and
toxic shock syndrome due to GAS. Diseases reportable to CDC but not in Illinois include animal
rabies, coccidioidomycosis and yellow fever. Animal rabies testing is only performed by state
laboratories so reporting is complete due to state laboratory reporting. In 2001, the 10 most
frequently reported notifiable infectious diseases in the United States were chlamydia, gonorrhea,
AIDS, salmonellosis, hepatitis A, shigellosis, tuberculosis, Lyme disease, hepatitis B and
syphilis.
In 2001, 65 different types of infectious diseases were reportable to IDPH (see page 1 and
2). Significant infectious disease rule changes went into effect on April 1, 2001. A new reporting
time frame of immediate reporting (within three hours) went into effect for anthrax, botulism,
plague, Q-fever, smallpox and tularemia, and for any suspected bioterrorism event. Diseases
added to the reportable list included infant or wound botulism, other types of pathogenic E. coli
such as enterotoxigenic, enteropathogenic or enterohemorrhagic (even non O157), hemolytic
uremic syndrome, campylobacter, cyclosporiasis, yersiniosis, chanchroid, potential human rabies
exposures, vancomycin-resistant S. aureus, ehrlichiosis, hantavirus, hepatitis C, group B strep
infections in those younger than 3 months, invasive S. pneumoniae infections with antibiograms
and unusual cases or clusters that may represent a public health threat. Diseases that were deleted
from the reportable disease list included intestinal worms, scarlet fever, animal bites,
streptococcal sore throat and trachoma. Reporting time frames were changed for anthrax,
foodborne botulism, hepatitis A, E. coli O157:H7, plague, rubella, smallpox, invasive group A
streptococcal infections and tularemia. Reporting methods were expanded to include electronic
or facsimile reporting. Laboratories also were obligated to forward isolates to the state lab for
Brucella, pathogenic E. coli, Legionella, Listeria, plague and invasive group A streptococcus.
Many of the reportable diseases are included in this annual report along with some nonreportable diseases of importance in 2001. Case numbers for the various infectious diseases listed
3
in this summary should be considered minimum estimates. There are several reasons why
reported numbers are lower than the actual incidence of disease: many individuals do not seek
medical care and thus are not diagnosed; some cases are diagnosed on a clinical basis without
confirmatory or supportive laboratory testing; and, among diagnosed cases, some are not
reported. These surveillance data are used to evaluate disease distribution trends over time
rather than to identify precisely the total number of cases occurring in the state.
The five most frequently reported nationally notifiable infectious diseases in Illinois were
chlamydia, gonorrhea, AIDS, Salmonella and Shigella. Diseases with increased reporting in 2001
over the previous five-year median included aseptic meningitis, H. influenzae, chlamydia,
histoplasmosis, Lyme disease, pertussis and invasive group A streptococcus. Several diseases for
which reporting requirements changed in 2001 had an increase in reporting including
campylobacter, group B streptococcus, S. pneumoniae, tularemia and yersiniosis. A large outbreak
of cryptosporidiosis resulted in an increase in this disease in 2001. The number of reported cases
of brucellosis, giardia, hepatitis A, HIV/AIDS, N. meningitidis, legionellosis, Salmonella,
Shigella, typhoid fever and varicella has been decreasing compared to the previous five-year
median.
Highlights of 2001 in Illinois included the appearance of WNV-infected birds and horses
late in the year. No human cases of WNV occurred in the state. In addition, there was a
heightened interest in bioterrorism after letters containing anthrax spores were discovered on the
East Coast. Both local and state Health Department personnel took numerous calls about
suspicious powders found at work sites and homes in Illinois, and the IDPH laboratory tested
many suspicious powders. Also, a large outbreak of cryptosporidiosis at a Tazewell County water
park was reported.
Studies mentioned in the text of this report will be referred to in the selected readings
section. The reporting of infectious diseases by physicians, laboratory and hospital personnel, and
local health departments is much appreciated. Without the support of the local health departments
in following up on disease reports, it would not be possible to publish this annual report. IDPH
hopes this information is useful and welcomes suggestions on additional information that would
be of use.
Useful Contact/Surveillance Information
IDPH Web site www.idph.state.il.us
To report cases, contact your local health department.
To refer isolates to the IDPH lab, ship to one of three locations:
Public Health Laboratory; 825 N. Rutledge St., Springfield IL 62761
Public Health Laboratory; 1155 S. Oakland Ave., P.O. Box 2797, Carbondale IL 62902-2797
Public Health Laboratory; 2121 W. Taylor St., Chicago, IL 60612
4
Illinois Counties
5
Acquired immune deficiency syndrome/Human immunodeficiency virus
Background
Following the first reports of cases in the summer of 1981, acquired immune deficiency
syndrome (AIDS) has become one of the major health problems to emerge in the past 25 years. In
1984, the human immunodeficiency virus (HIV) was identified as the causative agent of AIDS. It
is spread by the exchange of blood, semen or vaginal secretions between individuals. The most
common routes of transmission are 1) having sex (anal, oral or vaginal) with an infected person,
2) sharing drug injection equipment with an infected person (including insulin or steroid needles),
and 3) from mother to infant (perinatal) before or at the time of birth or through breast-feeding.
Within weeks to months after infection with HIV, some individuals develop a flu-like
illness. After this initial illness, individuals with HIV may remain free of clinical signs for months
to years. Since the progression of HIV to AIDS is as high as 50 percent among untreated infected
adults monitored for 10 years, assessing the impact of the epidemic in Illinois has relied mainly on
the reporting of cases that met the AIDS definition.
Clinical indicators of HIV infection may include lymphadenopathy, chronic diarrhea,
weight loss, fever and fatigue followed by opportunistic infections. HIV may progress to AIDS,
which includes a variety of late-term clinical manifestations including low T-cell counts.
Opportunistic infections associated with AIDS include Pneumocystis carinii pneumonia, chronic
cryptosporidiosis, central nervous system toxoplasmosis, candidiasis, disseminated
cryptococcosis, tuberculosis, disseminated atypical mycobacteriosis and some forms of
cytomegalovirus infection. Some cancers also may be associated with AIDS (e.g., Kaposi
sarcoma, primary B-cell lymphoma of the brain, invasive cervical cancer and non-Hodgkin’s
lymphoma).
Increased knowledge of the disease and improved diagnostic and treatment methods have
led to significant advances in the clinical management of HIV and resulted in a delay in the
progression from HIV to AIDS and a reduction in AIDS morbidity and mortality. A number of
antiretroviral agents are available for treatment of HIV/AIDS, and combination therapies have
been shown to prolong and improve the quality of life for those who are infected.
Case definition
In the state of Illinois, AIDS has always been reported by name, while HIV reporting was
without patient identifiers until July 1, 1999. For HIV reporting, this meant that individuals with
multiple positive test results for HIV were counted as new HIV cases each time they tested
positive. On July 1, 1999, reporting of HIV by a patient code number (PCN) became mandatory in
Illinois. The PCN is a coding system that permits duplicate reports to be identified but is not
specific enough to permit identification of an individual person. It is expected that use of the PCN
will allow enhanced surveillance for HIV infection and eliminate duplicate reporting. Prevalent
cases of HIV treated in Illinois are also reportable using the PCN system.
The case definition for AIDS has changed three times, which should be taken into account
when reviewing trends over time. The changes can be referred to as pre-1987, the 1987 revision
and the 1993 revision. To review the case definitions and how they have changed over time, the
following MMWRs (Morbidity and Mortality Weekly Report) should be reviewed:
6
1)
2)
3)
4)
Review of the CDC surveillance case definition for acquired immunodeficiency syndrome.
MMWR 1987;36 (Suppl:)1-15s.
1993 revised classification system for HIV infection and expanded surveillance case
definition for AIDS among adolescents and adults. MMWR 1992;41(RR-17):1-19.
1994 revised classification system for human immunodeficiency virus infection in children
less than 13 years of age. MMWR 1994;43(RR-12): 1-19.
Case definitions for infectious conditions under public health surveillance. MMWR
1997;46(RR-10): 5-6.
Additional changes, including a revised case definition for HIV infection in adults and
children, became effective January 1, 2000. For information about this latest revision, see
“Guidelines for national human immunodeficiency virus case surveillance, including monitoring
for human immunodeficiency virus infection and acquired immunodeficiency syndrome,”
MMWR 1999; 48 (No. RR-13).
Descriptive epidemiology
•
Cumulative AIDS cases reported in Illinois (1981 through 2001) – 26,146.
•
Number of AIDS cases reported in calendar year 2001 – 1,212. The number of AIDS cases
declined from 2000 to 2001 (Figure 1). The number of reported HIV cases was 1,542, a
decline over the 2,625 reported in 2000.
•
Mode of transmission among all AIDS cases reported in Illinois in 2001 is shown in
Figure 2 and for HIV in Figure 3.
•
The majority of reported AIDS cases in 2001 were in males (964 cases or 80 percent).
For all cases reported among males, men who have sex with men (MSM) accounted for
the largest number of AIDS cases (472 cases or 49 percent), followed by injection drug use
(IDU) with 177 cases or 18 percent (Figure 4). The majority of reported HIV cases in
2001 were in males (1,083 or 70 percent). For all cases reported among males, men who
have sex with men accounted for the largest number of HIV cases (530 or 49 percent),
followed by IDUs with 166 or 15 percent (Figure 5).
•
Reported cases of AIDS among females accounted for 248 cases or 20 percent of the total
AIDS cases reported in 2001. Among females, heterosexual contact accounted for 83
cases or 33 percent of the total, with IDU accounting for 70 cases or 28 percent (Figure 6).
Reported cases of HIV among females accounted for 459 or 30 percent of the total
reported HIV cases in 2001. Among females, heterosexual contact accounted for 140 or 31
percent of the total HIV cases reported, with IDU accounting for 92 or 20 percent (Figure
7).
•
African Americans, who represent 15 percent of the state’s population, accounted for 58
percent, or 701 of the AIDS cases reported in 2001. This represents an increase since
1994 when 47 percent of cases reported were among African Americans (Figure 8).
African Americans accounted for 869 or 56 percent of the reported HIV cases in 2001.
•
Heterosexual contact as the mode of transmission accounted for 12 percent, or 147, of all
the reported AIDS cases in 2001. This represents an increase since 1994 when 9 percent
of all AIDS cases reported heterosexual contact as the mode of transmission (Figure 9).
Heterosexual contact as the mode of transmission accounted for 14 percent, or 218, of the
7
•
total reported HIV cases.
In 2001, metropolitan Chicago cases comprised 81 percent of the total, with Chicago
accounting for 63 percent of the total reported AIDS cases. Reported AIDS cases residing
outside of the Chicago metropolitan area represented 19 percent of the state total.
Metropolitan Chicago cases comprised 75 percent of the total reported HIV cases, with
Chicago accounting for 58 percent of the total. Reported HIV cases residing outside of the
Chicago metropolitan area represented 25 percent of the state total.
Summary
More than 1,000 AIDS cases and 1,542 HIV cases were reported in Illinois between
January 1 and December 31, 2001. Most reported AIDS and HIV cases were in males. The most
common risk factor for transmission for HIV and AIDS in males was MSM. Heterosexual contact
was the most common risk factor for females for HIV and AIDS, followed by IDU. The decreased
incidence of AIDS is probably due to new antiretroviral treatments.
8
9
10
11
12
Amebiasis
Background
Entamoeba histolytica is a protozoan parasite that exists in two forms: the cyst and the
trophozoite. It is an important health risk to travelers to the Indian subcontinent, southern and
western Africa, the Far East, and areas of South and Central America. Intestinal disease can range
from mild diarrhea to dysentery with fever, chills and bloody or mucoid diarrhea. Extraintestinal
amebiasis also can occur. Humans are the reservoir for Entamoeba histolytica. Transmission
occurs by ingestion of cysts in fecally contaminated food or water or through oral-anal contact.
The incubation period ranges from two to four weeks.
Case definition
The CDC case definition used by IDPH for a confirmed case is as follows: a clinically
compatible illness that is laboratory confirmed (demonstration of cysts or trophozoites of E.
histolytica in stool, or demonstration of trophozoites in tissue biopsy, or ulcer scraping by culture
or histopathology). The definition for a case of extraintestinal amebiasis is a parasitologically
confirmed infection of extraintestinal tissue; or, among symptomatic persons with clinical and/or
radiographic findings consistent with extraintestinal infection, demonstration of specific antibody
against E. histolytica as measured by indirect hemagglutination or enzyme-linked immunosorbent
assay (ELISA).
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 65 (five-year median=59). From 1996 to
2001, the number of cases reported per year ranged from 47 to 69 (Figure 10).
•
Age – Cases ranged from 3 to 83 years of age (mean=34) (Figure 11).
•
Gender – Among 30- to 49-year-olds, there were 24 male cases and only 10 females.
Overall, males accounted for 67 percent of cases, a significantly higher proportion than in
the Illinois population (49 percent male).
•
Race/ethnicity – 71 percent were white, 21 percent were African American and seven
percent were Asian; 28 percent identified themselves as Hispanic, a significantly higher
proportion than in the total Illinois population (12 percent).
•
Seasonal variation – There appeared to be no seasonal peak in amebiasis.
•
Symptoms – Diarrhea was reported by 89 percent of cases and vomiting by 17 percent of
cases. Three were reported to have the organism identified in extraintestinal tissue.
•
Treatment – 83 percent of cases were known to be treated for their illness. Of cases where
the information was known, one was hospitalized.
•
Risk factors – Traveling outside the country (19 percent), drinking from a private water
supply (13 percent), swimming in non-chlorinated water (7 percent) and contact with
someone in a day care center (12 percent) were reported risk factors. In the four weeks
prior to illness, three individuals reported a specific travel destination outside the country.
Summary
There were 47 to 69 cases of amebiasis reported in Illinois each year from 1996 to 2001.
Amebiasis was significantly more common in those reporting Hispanic ethnicity. More males
than females were affected.
13
14
Bioterrorism
Background
Bioterrorism is the use or threatened use of biologic agents against a person, group or
population to create fear or illnesses for purposes of intimidation, gaining an advantage,
interruption of normal activities or ideologic objectives. A bioterrorist attack using anthrax
through the U.S. mail system occurred for the first time in 2001 in states in the Eastern United.
States. Although these attacks took place outside of Illinois, the effects of this attack were felt in
the state.
Possible bioterrorism agents are categorized. Category A agents have the greatest potential
for harm if used in bioterrorism because they are easily disseminated and transmitted person to
person; cause high mortality; severely affect public health; and could cause social disruption.
These agents include anthrax, botulism, plague, smallpox, tularemia and viral hemorrhagic fevers.
Anthrax
B. anthracis was the organism used in the 2001 bioterrorism attack in the United States.
Unlike other bacillus species like B. cereus and B. subtilis, B. anthracis is nonmotile, nonhemolytic, grows at 27° C and forms large colonies. B. anthracis is a gram positive bacillus. It
forms resistant spores that can survive in the soil for decades. Spores entering the lung can
germinate up to 60 days later. The median lethal inhalation dose is 2,500 to 55,000 spores.
Anthrax occurs in humans and in farm and wild animals. In the United States, less than one case
per year was reported in the 20 years prior to 2001. Anthrax can be acquired by inhalation,
ingestion or cutaneous contact with B. anthracis spores. Naturally occurring human infection
usually occurs following contact with livestock or animal products. Historically, inhalation
anthrax is a rare occupational disease.
Most acute respiratory illnesses are caused by viral pathogens including influenza virus,
parainfluenza virus, respiratory syncytial virus, rhinovirus and adenovirus.
During the 2001 attack, the average incubation period for the inhalation cases was four
days (ranged four days-six days). The initial phase of inhalation anthrax is a nonspecific illness
characterized by fever, myalgia, nonproductive cough and chest or abdominal pain. Disease
progresses to include acute dyspnea, diaphoresis and cyanosis, which can be followed by shock
and death. Once the bacteria multiply, three toxic proteins are released: lethal factor, edema
factor and protective antigen. These three proteins result in hemorrhagic necrosis of the
mediastinal lymph nodes. The most common pathological findings in inhalational anthrax include
hemorrhagic thoracic lymphadenitis, hemorrhagic mediastinitis and large volume of hemorrhagic
pleural effusions.
Cutaneous anthrax occurs when spores are introduced into cuts or abrasions. Cutaneous
anthrax accounts for more than 95 percent of reported cases in the world. Most are due to
occupational exposure. After an incubation period of one to seven days, a painless pruritic papule
appears, resembling an insect bite. The lesion progresses to a black eschar with edema. The
differential diagnoses may include brown recluse spider bite, erysipelas, cellulitis, cat scratch
disease, ecthyma gangrenosum and ulceroglandular tularemia.
Another form of anthrax is gastrointestinal anthrax, which occurs after anthrax spores are
swallowed. The spectrum of disease can range from asymptomatic to fatal. Anthrax spores can
cause lesions from the oral cavity to the cecum.
Blood cultures and polymerase chain reaction (PCR) of sterile fluids such as blood or
15
pleural fluid are important tools to diagnose inhalation anthrax. Gram stain and culture of the
lesion are recommended for cutaneous anthrax. B. anthracis grows readily, can be evaluated in a
biosafety level 2 (BSL-2) facility, and has characteristic gram stain morphology.
The anthrax vaccine has been licensed by the federal Food and Drug Administration
(FDA) since 1970 for pre-exposure purposes for individuals with occupational exposure. These
individuals include woolen mill workers, laboratory workers and veterinarians. Members of the
U.S. armed forces have received anthrax vaccinations since 1998. Anthrax vaccination consists of
six doses over 18 months, followed by an annual booster. The vaccine has not yet been approved
by the FDA for post-exposure use. The Advisory Committee on Immunization Practices (ACIP)
recommends that the pre-exposure use of the vaccine be based on risk of exposure. Groups at risk
for exposure should be given priority for immunization. These include laboratory personnel
handling environmental specimens or confirmatory testing for B. anthracis and workers in other
fields where repeated exposure to aerosolized B. anthracis may occur. Laboratory workers in
BSL-2 facilities are not recommended for vaccination. For persons exposed to anthrax, both
antibiotics and vaccination are recommended post-exposure. Vaccine would be used under an
investigational new drug (IND) application with the FDA. Antimicrobial prophylaxis should be
used for 60 days if antibiotics are the only treatment and for at least 30 days if vaccination is also
used.
Before October 2001, the last case of inhalation anthrax in the United States occurred in
1976. Twenty-two cases of anthrax (11 confirmed inhalation; seven confirmed and four suspected
cutaneous) were identified in the 2001 outbreak in the United States. The first case of anthrax due
to bioterrorism in the United States in 2001 was recognized due to a widened mediastinum on
initial chest radiograph and hemorrhagic spinal fluid with gram positive bacilli on spinal fluid.
Five cases of inhalation anthrax were fatal. The first case of confirmed inhalation anthrax was
reported on October 4, 2001. Cases were reported from Connecticut and the District of Columbia,
Florida, New Jersey and New York. The source of the B. anthracis was suspected to be five letters
sent through the United States Postal Service. Fifty-five percent of patients who were given
multidrug antibiotic regimens survived. An infant developed cutaneous anthrax after visiting a
television network facility. Initial diagnosis was a brown recluse spider bite. Approximately
10,000 people received antibiotics as a consequence of suspected exposure to anthrax spores in
the 2001 attack. The adherence rates in the 2001 outbreak ranged from 45 percent to 85 percent
and depended on the rate of adverse reactions, method of study and perception of risk.
Local and state health departments in Illinois received numerous questions from citizens,
physicians and emergency responders about anthrax. The first specimens to reach the IDPH
laboratory for anthrax testing arrived on October 8, 2001. Specimens included letters, packages,
clothing and environmental samples taken from buildings. As the volume of environmental
samples increased and the time burden associated with processing of these samples grew, the FBI
began to prioritize which specimens needed to be tested first. Laboratory staff looked for typical
colony morphology, hemolysis and motility of culture specimens to determine if B. anthracis was
present. The turnaround time during this crisis time was 48-72 hours. No samples positive for B.
anthracis were identified in Illinois although more than 1,700 specimens were processed.
Antibiotics that can be used for treatment of inhalation anthrax include ciprofloxacin,
doxycycline and penicillin G procaine. Possibility of antibiotic resistance should be considered
when selecting therapy. Prophylaxis is indicated for persons exposed to an airspace contaminated
with aerosolized B. anthracis. Prophylaxis is not indicated for prevention of cutaneous anthrax.
16
Smallpox
Another category A agent is smallpox. There are more than 117 million U.S. residents
who have never been vaccinated for smallpox. Routine vaccination for smallpox stopped in 1972
in the United States and the last case of endemic smallpox in the world occurred in Somalia in
1977. In an epidemic of smallpox in Boston from 1901 to 1903, 17 percent of smallpox cases
died. Most deaths occurred seven to 14 days after symptom onset. Smallpox spreads from person
to person mainly by droplet nuclei or aerosols expelled by infected persons and by direct contact.
The incubation period is seven to 17 days. Symptoms include fever, headache, backache and
exanthem. The rash distribution is centrifugal with greater involvement of the face and
extremities than the trunk. Rash lesions appear in crops and progress to pustules and then scabs
that fall off. Complications of vaccination include postvaccinal encephalitis, progressive vaccinia,
eczema vaccinatum, generalized vaccinia and inadvertent inoculation.
Plague
Plague, caused by Yersinia pestis, also has been classified as a category A critical
biological agent by the CDC. Most naturally occurring human cases, which cluster in the
southwestern United States, arise from bites from infected fleas, or from contact with infected
rabbits, wild rodents or domestic cats. Dog and cat fleas are not efficient vectors of the disease.
Between five and 15 human plague cases occur in the United States each year, approximately 15
percent die. Plague causes a febrile illness with three clinical manifestations: bubonic,
septicemic and pneumonic.
Hemorrhagic fever viruses
Hemorrhagic fever viruses are category A agents that cause fever and a bleeding diathesis
caused by viruses from four families. These viruses are transmitted to humans via contact with
infected animal reservoirs or arthropod vectors. A case of Lassa fever was imported into Illinois
approximately 15 years ago and no imported cases have been reported since that time.
Other
Another possible way to transmit a bioterrorist agent is through the food chain. Food
contamination usually comes from animal feces, environmental organisms or food handlers.
Pathogens that can be transmitted by infected food handlers include norovirus, hepatitis A,
Salmonella typhi, Shigella, Staphylococcus aureus and Streptococcus pyogenes. It would be
difficult to contaminate municipal water supplies because of dilution, inactivation by disinfectants
or sunlight, filtration and the small amount of water ingested directly from the tap.
Public health actions and decisions that need to be made if a covert bioterrorist threat
occurs include: 1) recognizing that an unusual event is occurring, 2) confirming the agent in the
laboratory, 3) finding cases through active surveillance, 4) determining the population at risk
through an epidemiologic study to find the exposure site, 5) informing the media and public about
who needs treatment or prophylaxis, 6) providing prophylaxis to individuals working on the
outbreak, 7) establishing a hotline or web site for information, 8) setting up mass prophylaxis
sites, staffing, delivering agents to the site and providing instructions for the public.
Suggested readings
Albert MR et al. Smallpox manifestations and survival during the Boston epidemic of
1901 to 1903. Ann Int Med 2002;137(12): 993-1000.
17
Anonymous. Use of anthrax vaccine in response to terrorism: Supplemental
recommendations of the Advisory Committee on Immunization Practices. MMWR 2002;
51(45):1024-6.
Bartlett JG, Inglesby TV, Borio L. Management of anthrax. CID 2002:35:851-8.
Bicknell WJ. The case for voluntary smallpox vaccination. NEJM 2002;346(17):1323-5.
Borio L, Frank D et al. Death due to bioterrorism-related inhalational anthrax. Report of
two patients. JAMA 2001;286(20):2554-9.
Borio L et al. Hemorrhagic fever viruses as biological weapons. Medical and public
health management. JAMA 2002:287(18):2391-405.
Brachman PS. Bioterrorism: An update with focus on anthrax. Am J Epi
2002:155(11):981-987.
Breman JG, Henderson DA. Diagnosis and management of smallpox. NEJM
2002;346(17): 1300-1308.
Bush LM, Abrams BH et al. Index case of fatal inhalational anthrax due to bioterrorism in
the United States. NEJM 2001;345(220:1607-10).
Giovachino M. Modeling the consequences of bioterrorism response. Mil Med
2001;166(11):925-30.
Glass TA, Schoch-Spara M. Bioterrorism and the people: How to vaccinate a city against
panic. CID 2002;34:217-23.
Golash R, Dworkin MS. Coping with the anthrax threat at the state level. ASM News
2002; 68(10). 494-8.
Heller MB, Bunning ML et al. Laboratory response to anthrax bioterrorism, New York
City, 2001. Emerging Inf Dis 2002;8(10):1096-1102.
Henderson DA et al. Smallpox as a biological weapon. Medical and public health
management. JAMA 1999;281(22):2127-37.
Horton HH, Misrahi JJ, Mathews G, Kocher P.Critical biological agents: Disease reporting
as a tool for determining bioterrorism preparedness. J Law, Medicine and Ethics 2002;20:262266.
Inglesby TV et al. Anthrax as a biological weapon, 2002. Updated recommendations for
management. JAMA 2002;287(170:2236-52.
Kuehnert MJ et al. Clinical features that discriminate inhalational anthrax from other
acute respiratory illnesses. CID 2003:36: 328-36.
Jernigan JA et al. Bioterrorism-related inhalational anthrax: The first 10 cases reported in
the United States. Emerg Inf Dis 2001;7(6):933-44.
Lanett C, Fauci AS.Bioterorrism on the home front. A new challenge for American
medicine. JAMA 2001;286(20):2595-7.
Mayer TA, Bersoff-Matcha S et al. Clinical presentation of inhalational anthrax following
bioterrorism exposure. Report of 2 surviving patients. JAMA 2001;286(20):2549-53.
MMWR. Laboratory security and emergency response guidance for laboratories working
with select agents. MMWR 2002;51(RR-19): 1-6.
Orloski KA, Lathrop SL. Plague: A veterinary perspective. JAVMA 2003;22(4):444-8.
Roche KJ, Chang MW et al. Cutaneous anthrax infection. NEJM 2001;345(22):1611.
Rotz LD, Khan AS, Lillibridge SR, Ostroff Sm and Hughes JM. Clinical issues in the
prophylaxis, diagnosis and treatment of anthrax. Emerging infectious diseases: 2002; 8(2):22230.
Sirisanthana T, Brown AE. Anthrax of the gastrointestinal tract. Emerging Inf Dis
18
2002;8(7): 649-52.
Swartz MN. Recognition and management of anthrax-An update. NEJM
2001;345(22):1621-6.
Weis CP et al. Secondary aerosolization of viable Bacillus anthracis spores in a
contaminated U.S. senate office. JAMA 2002;288(22):2853-8.
Wiesen AR, Littell CT. Relationship between pre-pregnancy anthrax vaccination and
pregnancy and birth outcomes among U.S. army women. JAMA 2002;287(12):1556-60.
19
Blastomycosis
Background
Blastomyces dermatitidis is a dimorphic fungus found in both Canada and the midwestern
United States. Blastomycosis is a zoonotic disease endemic in the midwestern United States.
Occasionally, outbreaks occur in areas outside the endemic areas. The ideal area for the mycelial
form of the organism is soil of warm, moist, wooded areas rich in organic debris. Recreational
activities along waterways are considered to be a major risk factor for infection. Transmission is
usually through inhalation of spore-laden dust. Blastomycosis most commonly presents as a
subacute pulmonary disease but can range from asymptomatic to disseminated disease. For
symptomatic infections, the incubation period ranges from 30 to 45 days. In a Canadian study
carried out in Manitoba residents, 65 percent of cases were male; 93 percent of cases had lung
involvement and 13 percent had bone involvement. The mortality rate was 6 percent. The annual
incidence rate in this study was 0.62 cases per 100,000 population.
Case definition
The case definition for confirmed blastomycosis in Illinois is culture confirmation of
Blastomyces dermatitidis. If the diagnosis was based on a needle aspirate or other diagnostic
specimen with demonstration of organism resembling Blastomyces or a presumptive
Blastomycosis culture, it is considered a probable case.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 47. From 1996 to 2001, the median number
of cases was 47 and cases per year ranged from 29 to 65 (Figure 12). The 2001 incidence
rate was 0.38 per 100,000 in Illinois.
•
Age – The mean age was 47 years (range 15 to 86) (Figure 13).
•
Gender – 62 percent were male.
•
Race/ethnicity –Two-thirds of the cases (68 percent) were white, 22 percent were African
American and 11 percent were other races; 13 percent were Hispanic.
•
Geographic distribution – More than half of the cases (57 percent) had residential
addresses in Cook or Lake counties.
•
Symptoms – Cough (80 percent), fever (67 percent), weight loss (54 percent), night
sweats (44 percent), malaise (42 percent), weakness (36 percent), chills (31 percent),
dyspnea (29 percent), skin lesions (29 percent), local swelling (29 percent), anorexia (27
percent), hemoptysis (22 percent) and arthritis (16 percent).
•
Diagnosis – 42 cases were culture confirmed from bronchial washing (13), lung tissue
(11), sputum (4), other site (10), multiple sites (3) and unknown site (1). Identification of
organisms resembling Blastomyces in tissues or secretions was used for diagnosis in five
cases.
•
Treatment – 85 percent of cases were hospitalized; two cases were fatal.
•
Risk factors – 34 percent of cases were smokers; 29 percent reported gardening as a
hobby. At least one case had diabetes and one case reported an underlying
immunosuppressive condition.
20
Summary
Forty-seven cases were reported in 2001. Blastomycosis cases occur predominantly in
adults. Many cases had symptoms of respiratory involvement, including cough, dyspnea or
hemoptysis. Approximately 89 percent of reported cases were confirmed by culture. Among
reported cases, 57 percent reported living in Cook or Lake counties.
Selected readings
Crampton TL, Light RB et al. Epidemiology and clinical spectrum of blastomycosis
diagnosed at Manitoba hospitals. Clin Inf Dis 2002;34:1310-6.
Hannah EL, Bailey AM et al. Public health response to 2 clinical cases of blastomycosis
in Colorado residents. Clin Inf Dis 2001;32:e151-e153.
21
Botulism
Background
Botulism is a neuroparalytic illness that results from infection with Clostridium botulinum.
There are three forms of botulism: foodborne, wound and intestinal (adult and infant). Intestinal
botulism is the most common form of botulism reported in the United States with about 100 cases
reported annually. About 24 cases of foodborne botulism are reported annually to CDC.
Diagnostic clues for foodborne botulism are primary neurologic symptoms including descending
paralysis, normal body temperature, diplopia, blurred vision and ptosis. Also, there is no altered
mental status. Differential diagnoses include myasthenia gravis and Guillain-Barré syndrome.
These can be differentiated using electromyography (EMG), the pattern of paralysis and reaction
to Tensilon®. The paralysis of botulism is flaccid, symmetrical and descending.
Foodborne botulism results from ingestion of preformed toxin present in contaminated
food. Wound botulism occurs after the causative organism contaminates a wound that is
anaerobic. Wound botulism has been described in users of black tar heroin in an investigation in
Washington state. Infant botulism results when swallowed spores germinate and temporarily
colonize the large intestine. Spores exist in soil and dust. Honey is an avoidable source of spores
for infants. Botulism in infants less than 12 months of age should be suspected when constipation,
lethargy, poor feeding, weak cry, bulbar palsies and failure to thrive are present. Treatment for
foodborne botulism is prompt administration of polyvalent equine source antitoxin, which can
decrease progression of paralysis but not reverse existing paralysis.
Diagnosis of infant botulism involves detection of botulinum toxin in stool or serum by
using a mouse neutralization assay or the isolation of toxigenic C. botulinum in the feces by
enrichment culture techniques. This testing of food and human specimens is performed at the
CDC laboratory. A request for this testing requires coordination with the local and state health
departments. Treatment of infant botulism is intensive care with mechanically-assisted ventilation
if necessary. Treatment may include botulinal immune globulin-IV.
Botulism is classified as a category A terrorism agent. There are various types of
Clostridium botulinum that can cause human illness, including types A, B, E and F.
Thirty-nine cases of foodborne botulism were reported to CDC in 2001. In Texas, an
outbreak implicated commercially produced chili sauce after time and temperature abuse. Ninetyseven cases of infant botulism and 19 cases of wound botulism also were reported to CDC in
2001.
If botulism is suspected, contact the local health department immediately. This will allow
for rapid investigation to identify the source. If the source was a commercial product, it should be
removed promptly from the market.
Case definition
Botulism, infant
Clinical illness may include poor feeding, constipation, failure to thrive and respiratory
failure. The case definition for infant botulism is a clinically compatible case that is laboratory
confirmed, occurring in a child younger than 1 year of age. Laboratory confirmation is isolation of
C. botulinum from stool or detection of botulinum toxin in stool or serum.
Botulism, foodborne
Clinical illness includes diplopia, blurred vision and bulbar weakness. Symmetric
22
paralysis may progress quickly. Laboratory confirmation consists of detection of
botulinum toxin in stool, serum or patient’s food or isolation of C. botulinum from stool.
A probable case is a clinically compatible case with an epidemiologic link (ingestion of
home-canned food within the previous 48 hours). A confirmed case is a clinically
compatible one that is laboratory confirmed or that occurs among persons who ate the
same food as persons who have laboratory-confirmed botulism.
Botulism, wound
Common symptoms include diplopia, blurred vision and bulbar weakness as well as
symmetric paralysis. Laboratory confirmation is by detection of botulinum toxin in serum or
isolation of C. botulinum from wound. A confirmed case is a clinically compatible illness that is
laboratory confirmed in a patient who has no suspected exposure to contaminated food and who
has a history of a fresh, contaminated wound during the two weeks before symptom onset.
Descriptive epidemiology
•
There were no laboratory-confirmed cases reported in Illinois in 2001.
Suggested readings
MMWR. Infant botulism-New York City, 2001-2002. MMWR 2003:52(2):21-24.
MMWR. Wound botulism among black tar heroin users-Washington, 2003. MMWR
2003;52(37).
MMWR. Outbreak of botulism type e associated with eating a beached whale-Western
Alaska, July 2002.
MMWR. Summary of notifiable diseases-United States 2001. MMWR 2003;50(53):p.xi.
23
Brucellosis
Background
Brucellosis is a systemic bacterial infection caused by Brucella species that can cause
intermittent or continuous fever and headache, sweating and arthralgia. Symptoms can last from
days to years. Brucella species considered of importance in human disease include B. abortus
(cattle are the primary reservoir), B. melitensis (sheep and goats are the primary reservoir) and B.
suis (swine are the primary reservoir). Dogs are reservoirs of B. canis but are not considered to be
an important public health concern in the United States. Brucellosis is a potential hazard to those
consuming unpasteurized milk or milk products. The disease is most common in residents or
travelers to the Mediterranean, Middle East, Mexico, and Central and South America.
Transmission is by contact with animal tissues, such as blood, urine, vaginal discharges, aborted
fetuses and placentas and by ingestion of raw milk or other dairy products. Veterinarians can
acquire infection from assisting in births of infected animals or exposure to B. abortus strain 19
vaccine. The incubation period varies from one to two months. Investigation of Brucella cases
could reveal foci of infection in U.S. livestock that should be investigated and eliminated.
However, the large majority of human Brucella cases are thought to be due to travel outside the
country and consumption of contaminated products from those countries. Brucella is also a
category A bioterrorism agent.
In the United States in 2001, 136 human brucellosis cases were reported to CDC. Human
brucellosis in California primarily affects Hispanics (77 percent of cases from 1973 to 1992).
Case definition
Illinois uses the CDC case definition for brucellosis. The case definition for a confirmed
case of brucellosis is a clinically compatible illness with one of the following laboratory findings:
isolation of Brucella from a clinical specimen, a four-fold or greater rise in Brucella agglutination
titer or demonstration of Brucella species in a clinical specimen by immunofluorescence. A
probable case is defined as a clinically compatible one that is epidemiologically linked to a
confirmed case or that has supportive serology (i.e., Brucella agglutination titer of > 160 in one
or more serum specimens obtained after symptom onset).
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 4 (2 confirmed cases) (Figure 14).
•
Age – Median age was 48 years (range 5 to 66).
•
Gender – three were males; one was female.
•
Race/ethnicity – 100 percent (4) were white.
•
Geographic distribution by residence– Cook County (3) and Kane County (1).
•
Case investigations – Available on three cases.
•
Diagnosis – Cases were identified through positive serology (1) and from culture (2). One
isolate was speciated and identified as B. melitensis.
•
Epidemiology – Two cases had unknown exposures; one case traveled to Greece and ate
goat cheese and one case traveled to Mexico and ate cheese.
24
Summary
In Illinois, brucellosis is an uncommon disease and tends to occur primarily in individuals
who have recently traveled to foreign countries and consumed unpasteurized dairy products. In
2001, there were four cases as compared to the previous five-year median of eight cases.
Suggested Readings
Fosgate GT, Carpenter TE et al. Time-space clustering of human brucellosis, California,
1973-1992. Emerging Inf Dis 2002;8(7):672-877.
25
Campylobacteriosis
Background
Campylobacteriosis is a zoonotic bacterial enteric disease caused primarily by
Campylobacter jejuni and occasionally by Campylobacter coli. Approximately 1 percent of the
population acquires Campylobacter each year in the United States. Of the 10 diseases under active
surveillance in the nine federal FoodNet sites (those caused by Campylobacter, Cryptosporidium,
Cyclospora, E. coli O157:H7, HUS, Listeria monocytogenes, Salmonella, Shigella, Vibrio and
Yersinia enterocolitica), data showed that Campylobacter comprised 34 percent of the reported
infections in 2001.
Campylobacter organisms are motile, gram-negative bacilli with a curved shape. Culture
can take 72-96 hours and the organisms grow best at 42º C. The reservoir for Campylobacter is in
animals, most commonly poultry and cattle. The most important mode of transmission is the
consumption and handling of raw poultry products. Campylobacter is found in approximately 80
percent of retail chicken meat. Campylobacter has been shown to be transmitted from puppies to
people. Campylobacter is also a cause of traveler’s diarrhea.
The infectious dose is large. The incubation period is two to five days. Symptoms may last
up to 10 days. They include diarrhea, abdominal pain and fever; however, many infections are
asymptomatic. Sequelae may include reactive arthritis, febrile convulsions, a typhoid-like
syndrome, Guillain-Barré syndrome or meningitis. C. jejuni infection is the most frequently
identified infection preceding Guillain-Barré syndrome. Reactive arthritis can occur seven to 10
days after diarrheal illness. C. jejuni bacteremia can occur in people with underlying conditions
such as liver cirrhosis, malignancy, HIV disease and other immunosuppressive diseases or
treatments and persons at the extremes of ages. Persons with HIV may experience bacteremia and
chronic diarrhea. Excretion of the organism can occur for two to seven weeks.
The disease is usually self-limiting although antibiotic treatment may be recommended for
extraintestinal infections or infections in immunocompromised persons.
Most cases occur during warmer months of the year and are sporadic, but occasionally
outbreaks occur. A Wisconsin outbreak in 2001 occurred due to transmission from drinking
unpasteurized milk. A case-control study of Campylobacter infections in Hawaii revealed that
consumption of chicken prepared in a commercial food establishment and prior antibiotic use
were significantly associated with illness. Some studies have shown an increased risk associated
with contact with pet dogs and cats, especially young pets or pets with diarrheal illness.
International travel is also a risk factor.
Prevention includes cooking meat thoroughly, avoiding cross contamination between
foods and hand washing after animal handling.
Prior to April 2001, reporting of Campylobacter was voluntary. On April 1, 2001,
Campylobacter reporting became mandatory in Illinois.
Case definition
The case definition for a confirmed case of campylobacteriosis in Illinois is a clinically
compatible illness with isolation of Campylobacter from any clinical specimen. A probable case is
a clinically compatible illness that is epidemiologically linked to a confirmed case.
26
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 1,265; incidence rate of 10 per 100,000
•
Gender – 52 percent were males.
•
Age – Mean age of reported cases was 37; highest incidence rate occurred in those less
than 5 years of age (Figure 15).
•
Race/ethnicity – The majority of cases (93 percent) were in whites, with 2 percent in
African Americans, 3 percent in Asians and 2 percent in other races. Those indicating
Hispanic ethnicity accounted for 11 percent of the cases. There was a significantly higher
proportion of whites with campylobacteriosis and a lower proportion of African
Americans with the disease than in the total Illinois population.
•
Seasonal variation – Campylobacteriosis was reported more often in the warmer months of
the year in Illinois (June to August) (Figure 16).
•
Past incidence – The case number was higher in 2001 compared to the five-year median of
874 cases (Figure 17).
Summary
Reporting of Campylobacter became mandatory on April 1, 2001, and the incidence of
Campylobacter increased from eight per 100,000 in 2000 to 10 per 100,000 in 2001.
Campylobacter infections occur more commonly from June to August. The incidence is highest
in 1- to 4-year-olds. Whites are more likely to be reported with Campylobacter infection than
other races.
Suggested readings
Altekruse SF, Tollefson LK. Human campylobacteriosis: a challenge for the veterinary
profession. JAVMA 2003; 223(4):445-52.
Baqar S, Rice B et al. Campylobacter jejuni enteritis. CID 2001;33:901-5.
Coker AO, Isokpehi RD et al. Human campylobacteriosis in developing countries. Emerg
Inf Dis 2002;8(3):237-43.
Effler P, Ieong —C et al. Sporadic Campylobacter jejuni infections in Hawaii:
Associations with prior antibiotic use and commercially prepared chicken. JID 2001:183:1152-5.
MMWR. Outbreak of Campylobacter jejuni infections associated with drinking
unpasteurized milk procured through a cow-leasing program- Wisconsin, 2001. MMWR
2002;51(25): 548-9.
Wolfs TFW, Duim B et al. Neonatal sepsis by Campylobacter jejuni: Genetically proven
transmission from a household puppy. CID 2001;32:e97-e99.
27
28
Central Nervous System Infections
General
Both aseptic meningitis and acute encephalitis are reportable in Illinois. The purpose of
this reporting is to identify arboviral infections. Control measures for arboviruses include public
education and mosquito abatement activities.
Aseptic meningitis is usually a self-limiting illness characterized by sudden onset of fever,
headache and stiff neck. A rash may be present along with vomiting, photophobia and nausea. In
the United States, enteroviruses cause most cases with known etiology. Some arboviral infections
may present as aseptic meningitis.
Acute infectious and post-infectious encephalitis are reportable in Illinois. Infections are
characterized by headache, high fever, meningeal signs, stupor, disorientation, coma, tremors,
convulsions or paralysis. In a study using National Hospital Discharge Survey data from 1988 to
1997, there were seven hospitalizations per 100,000 for encephalitis and 1,400 deaths annually.
For about 59 percent of encephalitis cases, the etiologic agent was not known or was not recorded.
The average cost of each hospitalization was $28,151.
The categorization of the aseptic meningitis and encephalitis cases was changed for 2001.
Aseptic meningitis and encephalitis were combined into an unknown etiology and known etiology
category so numbers are not directly comparable to previous years. Arbovirus infections were put
in a third section (See Table 1).
Table 1. Categorization of aseptic meningitis and encephalitis, 2001
Type of infection
Number
Percent
Arbovirus
California encephalitis
5
Saint Louis encephalitis
0
West Nile virus
0
0.3
Known etiology
Aseptic meningitis
166
10.6
11
0.7
1,291
82.7
89
5.7
Encephalitis
Unknown etiology
Aseptic meningitis
Encephalitis
TOTAL
1,562
29
Arboviral infections
Background
Some forms of infectious encephalitis are caused by mosquito-borne arboviruses that may
not always result in the “classical” encephalitis presentation. Arboviruses that cause encephalitis
are members of the Togaviridae, Flaviviridae or Bunyaviridae families. Humans and domestic
animals, such as horses, can develop clinical disease but are usually dead-end hosts because they
do not develop sufficient viremia to contribute to the transmission cycle. Arbovirus infections
may present as aseptic meningitis. Arboviral infections that have been reported in Illinois
residents include those due to St. Louis encephalitis (SLE), California (LaCrosse) (LAC)
encephalitis and western equine encephalitis (WEE) viruses. WEE has not been seen in Illinois for
a long time.
During the period from June 15 through October 31, physicians and laboratories in Illinois
are encouraged to submit cerebrospinal fluid from aseptic meningitis and encephalitis cases to the
IDPH laboratory for further testing. In addition, acute and convalescent serum samples are
requested for testing for arboviral antibody. The CSF is examined for antibodies to LAC, SLE,
eastern equine encephalitis and WEE viruses and cultured for enteroviruses.
WNV is a flavivirus in the Japanese encephalitis antigenic complex. This complex
includes Japanese encephalitis in Asia, St. Louis encephalitis in North and South America, and
Kunjin and Murray Valley encephalitis in Australia. Birds become infected from mosquitoes.
Infected ticks and bird-bird transmission may also occur. The amplifying vertebrate hosts are
birds. Culex mosquitoes are the primary vector. Mosquito pools positive in Illinois for WNV in
2001 were Culex species.
In 2001, the WNV outbreak in the United States expanded to 27 states and Washington,
D.C. Canada also identified WNV activity that year. In 2001, 66 persons with WNV, including
nine fatalities, were reported from 10 states. Other positive WNV results included 7,332 birds,
919 mosquito pools and 731 horses. Peak incidence occurred from late August to early
September. In the United States most human illnesses have occurred in August and September.
Older persons (greater than 50 years of age) were at increased risk for severe illness.
The incubation period for WNV is three to 14 days in humans. Most human infections are
not clinically apparent but febrile illness (fever, headache, backache, myalgia) is not uncommon.
A rash also may occur. A serosurvey in New York City showed that one in 150 infections
resulted in meningitis or encephalitis. Cerebrospinal fluid showed normal glucose level, elevated
protein (up to 900 mg percent) and lymphocytic pleocytosis (10-100 cells/mm3). Older age was a
risk factor for death from WNV. Encephalitis, severe muscle weakness and change in
consciousness were risk factors predicting death. WNV produces a viremia that tends to disappear
with the onset of clinical symptoms. IgM antibodies can persist for up to a year following
infection.
LAC virus is the main cause of pediatric encephalitis in the United States. In 2001, LAC
was the most commonly identified arbovirus in Illinois. The illness occurs mostly in children
younger than 15 years of age (the elderly are at greatest risk of SLE). In Illinois, cases of LAC
virus infection are most often reported from Peoria, Tazewell and Woodford counties. The main
vector is thought to be Ochlerotatus triseriatus.
In a study of Tennessee La Crosse encephalitis cases in children, the following factors
were identified as risk factors for infection: number of hours per day spent outdoors, living in a
residence with one or more tree holes within 100 meters and burden of Aedes albopictus around
30
the residence. In this study, the most common symptoms included fever, headache, vomiting and
behavioral changes. Twenty-five percent of cases had seizures. Use of insect repellent was not
associated with protection from illness.
SLE can also be identified in persons in Illinois. Several epidemics of this disease have
occurred in the state, including a large outbreak in 1975. A study in Florida found that a drought
period preceded its 1986 through 1991 SLE outbreak. During drought periods, birds may
congregate thereby facilitating transmission of SLE. When the drought ends, the birds disperse
and may initiate an epizootic.
Arboviral encephalitis prevention includes limiting mosquito bites in humans and reducing
mosquito habitat. Mosquito bites can be minimized by using appropriate repellents, by avoiding
the outdoors during peak mosquito feeding times and by repairing screens on windows and doors.
The use of repellents containing N,N-diethyl-3-methylbenzamide (DEET) provides the best
protection against mosquitoes. The higher the concentration of DEET up to 50 percent, the longer
the protection against mosquitoes. For instance, concentrations of DEET of 24 percent protect for
302 minutes while concentrations of 5 percent protect for 88 minutes. Removing tires and other
outdoor water receptacles, sealing tree holes and clearing clogged rain gutters can minimize the
habitat suitable for mosquitoes capable of transmitting LAC. Prevention involves personal
protective behaviors and mosquito control activities.
Case definition
The case definition for a confirmed case of arboviral encephalitis in Illinois is a clinically
compatible illness that is laboratory confirmed. The laboratory criteria are a fourfold or greater
rise in serum antibody titer; or isolation of virus from, or demonstration of viral antigen in, tissue,
blood, CSF or other body fluid; or specific IgM antibody in CSF. A probable case of arboviral
encephalitis is a clinically compatible illness occurring during the season when arbovirus
transmission is likely to occur and with the following supportive serology: a stable (twofold or
smaller change) elevated antibody titer to an arbovirus, e.g., > 320 by hemagglutination
inhibition, > 128 by complement fixation (CF), > 256 by IF, > 160 by neutralization, or a positive
serologic result by enzyme immunoassay (EIA). The case definition for post-infectious
encephalitis is a clinically compatible illness diagnosed by a physician as post-infectious
encephalitis. The case definition for primary encephalitis is a clinically compatible illness
diagnosed by a physician.
Descriptive epidemiology
More than 1,300 specimens (CSF or serum) from patients were tested for arboviruses.
LaCrosse encephalitis surveillance
The five 2001 LAC encephalitis cases resided in Cook (2), Peoria (1) Fulton (1) and
JoDaviess (1) counties and were from 4 to 78 years of age. Three cases were younger than 15.
Three cases presented with aseptic meningitis and two with encephalitis. Four cases were
confirmed and one was probable. Three cases had onset in July, one in August and one in
September. Environmental surveys to identify mosquito breeding sites were conducted in some
counties. Near the residence of the JoDaviess County case there was a large ditch with tires. Near
the residence of the Peoria County case, there was also an accumulation of about 100 tires, which
was referred to the Environmental Protection Agency for cleanup. Mosquito breeding sites were
not found at the Fulton County residence. Environmental investigations were not conducted for
31
the other two cases. No LAC cases were fatal.
•
Past incidence – The reported cases of LAC in Illinois are as follows: 1990 (1), 1991 (15),
1992 (7), 1993 (2), 1994 (6), 1995 (5), 1996 (13), 1997 (3), 1998 (4), 1999 (3), 2000 (3)
and 2001 (5) (Figure 22).
SLE surveillance
•
Reported SLE cases in Illinois were few from 1990 to 2001. There were two cases in 1993
and one case in 1995; no cases were reported in 1990-1992, 1994 and 1996-2001.
West Nile virus surveillance
Bird, mosquito pool, horse and human surveillance for WNV was conducted in 2001.
Bird testing
A total of 284 suitable dead birds were submitted for WNV testing in 2001. To be
considered suitable, birds had to be the correct species (blue jay, raptor or crow) and could not be
too decomposed for testing. Birds were necropsied at the Illinois Department of Agriculture
(IDOA) laboratory in Galesburg. Histopathology and gross pathology did not appear to be useful
in identifying birds positive for WNV. Starting in mid-June, the Galesburg laboratory began
testing bird tissues for WNV by immunohistochemistry testing (IHC).
Tissues from each bird were submitted to the National Wildlife Health Center (NWHC),
United States Geological Survey laboratory in Madison, Wisconsin, for confirmatory testing by
polymerase chain reaction (PCR) and/or virus isolation. The testing procedure at the NWHC
involves putting samples in cell culture for virus isolation if they have not previously been tested
for WNV. PCR is used to confirm virus isolation results. If the sample has been previously
tested positive, the NWHC confirms the result with PCR. The Wisconsin laboratory tested 279 of
the 284 Illinois birds (98 percent) submitted. Dead birds were classified as positive or negative
based on confirmatory testing at the NWHC laboratory. Birds that were not tested at the NWHC
laboratory were classified as positive based on IHC results.
The first WNV positive bird collection was from Mount Prospect in Cook County on
August 23. Eighty-three percent of submitted dead birds were collected in the month of
September (Figure 23). The last positive bird of the season was collected on October 8 from Kane
County. The percentage of submitted birds testing positive for WNV was 49 percent (138 of
284).
The sensitivity of the IHC performed at the IDOA laboratory as compared to the
confirmatory testing at NWHC was 97 percent. The specificity of the IHC as compared to the
confirmatory testing was 90 percent. Inconclusive IHCs were excluded from the sensitivity and
specificity calculations (Tables 2a and 2b).
The highest percentage of positives in birds tested was found in crows (57 percent),
followed by blue jays (25 percent) and raptors (8 percent). The types of raptors submitted were
described as red-tailed hawk (6), hawk, not further specified (9), great horned owl (5), owl, not
further specified (4) and kestrel (1).
Birds were submitted from 39 of the 102 Illinois counties (Figure 24): Bond (1), Bureau
(1), Carroll (1), Champaign (3), Cook, including Chicago (151), Crawford (1), DeKalb (3),
Douglas (1), DuPage (36), Henry (2), Jackson (1), Jasper (1), Kane (1), Kankakee (4), Kendall
(4), Knox (4), LaSalle (1), Lake (13), LaSalle (3), Lee (3), Livingston (1), Macoupin (1), Madison
(2), McDonough (1), McHenry (4), McLean (3), Morgan (1), Ogle (2), Piatt (1), Saline (1),
Sangamon (5), St. Clair (1), Stark (1), Stephenson (1), Tazewell (1), Vermilion (1), Whiteside (2),
Will (11) and Winnebago (5). The following seven Illinois counties had birds identified as
32
positive for WNV: Cook (103), Crawford (1), DuPage (21), Kane (1), Lake (6), McHenry (1) and
Will (5). In the city of Chicago, 44 birds were identified as positive for WNV. All positive birds,
except the one from Crawford County, were collected from the northeastern corner of the state.
WNV serology results on wild birds trapped in the state
Each year, wild birds are trapped in various areas in the state. In 2001, their blood was
tested by IgM ELISA for eastern equine encephalitis, St. Louis encephalitis and West Nile virus.
In 2001, 7,132 wild birds were tested in 32 counties within the state. No trapped wild birds tested
positive for arboviruses in 2001.
WNV mosquito pool testing
The Northwest Mosquito Abatement District performed the VecTest WNV test on
mosquito pools in Cook County. The positive pools were in Arlington Heights (5), Mount
Prospect (4), Palatine (3), Wheeling (2), Park Ridge (2), Northfield Township/Allison Woods (2),
Schaumburg (1) and Des Plaines (1). In 2001, 81 Culex mosquito pools were tested. A total of
16,213 mosquitoes were tested; 15,922 were Culex spp. and 291 were Aedes vexans. All A. vexan
pools were negative for WNV by the VecTest and PCR. Twenty Culex spp pools tested positive
via the TaqMan RT-PCR and 13 were positive using the VecTest. All the VecTest positives were
also TaqMan positive. The first positive mosquito pool was collected on August 15, which was
before the collection date (August 23) of the first positive bird. The last positive mosquito pool
was collected on October 12.
WNV horse testing
Forty-three horses stabled in Illinois were known to be tested for WNV by serologic tests,
virus isolation or PCR at the United States Department of Agriculture laboratory in Ames, Iowa.
Fourteen horses were tested for export purposes. Sera from 20 horses was tested due to concern
from the owner about WNV in the state; none were positive. Sera from nine horses was collected
by state or federal veterinarians after a report of clinical signs consistent with WNV. Two horses
were identified as positive for WNV, one in Cook County and one in Kane County. The horse
stabled in Arlington Heights in Cook County was a 5-year-old gelding with no travel history. The
horse developed neurologic signs beginning on September 30, 2001, and had been vaccinated for
WNV approximately five days prior to onset. The horse was confirmed as positive by IgM
ELISA and plaque reduction neutralization tests for WNV. The USDA laboratory believes this to
be a confirmed case because IgM would not be expected with this vaccination history. The horse
survived. The second horse was a 20-year-old horse stabled in Dundee, Illinois, in Kane County.
It was euthanized following neurologic disease that began approximately September 13. The
horse had pathologic evidence of equine protozoal myelitis, which can cause neurologic disease,
but was also polymerase chain reaction positive for WNV at the USDA laboratory in Ames, Iowa.
Virus isolation tests were negative, which is not uncommon with equine cases of WNV. This
case was considered a probable case of WNV by the USDA.
Conclusions
No humans tested positive for WNV in 2001. However, dead crows, blue jays and raptors
tested positive for WNV in seven counties in Illinois, mostly in the northeastern part of the state.
Almost half of all submitted dead birds were positive for WNV. Birds in Indiana, Iowa, Missouri
and Wisconsin also tested positive for WNV indicating that WNV could be present in areas of
33
Illinois adjacent to these states. Positive dead birds were collected in Illinois between August 23
and October 8. Positive mosquito pools were collected between August 15 and October 12. Two
horses stabled in the northeastern part of the state tested positive for WNV after onset of
neurologic illness in mid-to late-September.
Summary
Because encephalitis cases are more commonly reported in the summer months in Illinois,
IDPH asks physicians to submit sera and cerebrospinal fluid to IDPH to establish the etiology and
to report individuals with acute encephalitis from June 15 to October 31 each year. There were
five cases of LAC encephalitis and no cases of SLE reported in 2001. WNV was identified for the
first time in the state, in dead birds and in horses. No human cases of WNV were identified in
2001 in Illinois.
Suggested readings
Craven RB, Roehrig JT. West Nile Virus. JAMA 2001;286(6):651-3.
Erwin PC, Jones TF et al. La Crosse encephalitis in Eastern Tennessee: Clinical,
environmental, and entomological characteristics from a blinded cohort study. AJE
2002;155:1060-5.
Fradin MS and Day JF. Comparative efficacy of insect repellents against mosquito bites.
NEJM 2002;347:13-8.
Khetsuriani N, Holman RC, Anderson LJ. Burden of encephalitis-associated
hospitalizations in the United States, 1988-1997.
Martin AA, Gubler DJ. West nile virus encephalitis: An emerging disease in the United
States. Clin Inf Dis 2001;33:1713-9.
Peterson LR, Marfin AA. West Nile Virus: A primer for the clinician. Ann Int Med
2002;137:173-9.
Shaman J, Day JF, Stieglitz. Drought-induced amplification of Saint Louis encephalitis
virus, Florida. Emerg Inf Dis 2002;8(6):575-80.
Table 2a. Laboratory testing for positive birds
Positive by IHC and confirmed positive
132
Positive by IHC only, no confirmatory testing
1
Negative by IHC, positive confirmatory testing
4
Inconclusive by IHC, positive confirmatory testing
1
TOTAL birds counted as positive
138
34
Table 2b. Laboratory testing for negative birds
Negative by IHC and confirmed negative
95
Negative by IHC, no confirmatory testing
4
Positive by IHC, negative confirmatory testing
10
No IHC performed, negative confirmatory testing
13
Inconclusive IHC, negative confirmatory testing
24
TOTAL birds counted as negative
146
Table 3. Types of birds submitted for testing for WNV, 2001
Type
Total submitted
Positive
Negative
Percent positive
Crow
223
127
96
57
Blue jay
36
9
27
25
Raptor
25
2
23
8
TOTAL
284
138
146
49
35
Figure 24. Dead bird testing for WNV by county
36
Aseptic meningitis or encephalitis of known etiology, excluding arboviruses
Background
Both aseptic meningitis and encephalitis are reportable in Illinois. One of the purposes of
this reporting is to identify arboviruses. Virus isolation is offered to all persons in the state with
aseptic meningitis or encephalitis, and this helps to identify the etiology of some cases. In 11
percent of aseptic meningitis and acute encephalitis cases reported, an etiology was determined.
Case definition
The case definition for aseptic meningitis in Illinois is a clinically compatible illness
diagnosed by a physician as aseptic meningitis with elevated white blood cells in the cerebrospinal
fluid (CSF) but no laboratory evidence of bacterial or fungal meningitis. For aseptic meningitis of
known etiology, a virus could be isolated from the person and no arbovirus was identified in the
person.
The case definition for primary encephalitis is a clinically compatible illness diagnosed by
a physician as primary encephalitis. For encephalitis of known etiology, a virus could be isolated
from the patient and there was no positive test for arboviruses.
Descriptive epidemiology
•
Number of cases - 177
•
Age - Median age is 8 years.
•
Gender - 54 percent of cases were male.
•
Race/ethnicity – 78 percent white, 20 percent African American and 1 percent Asian; 16
percent Hispanic.
•
Seasonal variation - Aseptic meningitis or encephalitis of known etiology, excluding
arboviruses, was most common from July through September (Figure 21).
•
Diagnosis – 177 cases were identified as having a virus as the etiologic agent. Viruses
identified as the etiologic agent were echovirus 18 (56), echovirus 13 (28), herpes simplex
(11), echovirus 6 (10), echovirus 11 (5), echovirus 9 (2) and one each for echovirus 16, 20,
21 and echovirus, not further specified. Other viruses identified as the etiologic agents
were coxsackie B2 (3), coxsackie B (2), coxsackie A16 (1), coxsackie B5 (1), coxsackie A
strain 9 (1), coxsackie, not further specified (1) and Epstein-Barr virus (1). Other viruses
were enterovirus 70 (1), enterovirus 71 (1), and enterovirus, not further specified (49). The
site of virus isolation for 88 cases was known including CSF (81), nasopharynx (1) and
other (6). Either acute and/or convalescent sera was submitted to the IDPH lab from 24
individuals. Both acute and convalescent sera were submitted for no persons, acute sera
only was submitted for 19 people and convalescent sera only was submitted for five
persons. No encephalitis cases with known etiology were reported to be fatalities. Fiftytwo persons were tested for WNV in CSF or serum and were negative.
Summary
In only 11 percent of encephalitis and aseptic meningitis cases was an etiologic agent
identified as the cause of illness. Echovirus 18 and 13 were the most common echoviruses
identified as the causative agents for aseptic meningitis and encephalitis cases. Enteroviruses, not
further specified, was also a frequent classification for etiology.
37
38
Aseptic meningitis or encephalitis of unknown etiology
Background
Both aseptic meningitis and encephalitis are reportable in Illinois. One of the purposes of
this reporting is to identify arboviruses. Although virus isolation and serologic testing for
arboviruses (during the appropriate season) is offered to all persons in the state with aseptic
meningitis or encephalitis, the etiology of many cases remains unknown.
Case definition
The case definition for aseptic meningitis in Illinois is a clinically compatible illness
diagnosed by a physician as aseptic meningitis with elevated white blood cells in the cerebrospinal
fluid (CSF) but no laboratory evidence of bacterial or fungal meningitis. For aseptic meningitis of
unknown etiology, no virus could be isolated from the person and testing for arboviruses was
negative.
The case definition for primary encephalitis is a clinically compatible illness diagnosed by
a physician as primary encephalitis. For encephalitis of unknown etiology, no virus could be
isolated from the patient and there were no positive tests for arboviruses.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 1,380
•
Age – Annual incidence rate highest in those less than 1 year of age (98 per 100,000)
(Figure 18). In all other age groups, the incidence rate was below 21 per 100,000. The
mean age of reported cases was 22.
•
Gender – 51 percent were male.
•
Race/ethnicity – 79 percent white, 19 percent African American and 2 percent Asian; 10
percent Hispanic.
•
Seasonal variation – Most common July through September (Figure 19); 1,073 cases had
onsets between June 15 and October 31 (307 had onsets outside of this time frame).
•
Geographic distribution – Highest annual incidence rates per 100,000 population for 2001
were in Scott (10.8), Tazewell (8.2), Coles (6.8), White (6.5) and Macon (6.4) counties
(Figure 20).
•
Diagnosis – Among cases with onset between June 15 and October 31, virus isolation was
attempted in 634 cases (59 percent); no viruses were isolated in this category. The cases
where a virus was isolated were included in the next section of known etiology.
Acute blood specimens were sent to the IDPH laboratory for 398 individuals; convalescent
blood specimens were submitted for 102 individuals. For 339 individuals, only an acute
serum specimen was collected; for 49 individuals only a convalescent serum was
submitted; and for 42 individuals, both acute and convalescent serum were obtained. Both
acute and convalescent specimens were obtained only for 42 of 1,073 (4 percent) of the
aseptic meningitis cases from June 15 through October 31. At the IDPH laboratory, these
specimens were tested for evidence of arbovirus infections (Saint Louis encephalitis
(SLE), LaCross encephalitis (LAC) and Eastern equine encephalitis (EEE). In addition,
595 persons with either aseptic meningitis or encephalitis tested negative for WNV. Such
testing of patients with presumed viral infections of the central nervous system (CNS) is
necessary to identify arboviral infections. However, testing of acute and convalescent sera
39
•
from only 4 percent of patients was probably inadequate to identify public health threats
due to mosquito-borne viruses. Cases of LAC encephalitis for 2001 are described in the
arbovirus section.
Outcome - Four fatalities occurred (three in encephalitis cases and one in an aseptic
meningitis case).
Summary
Cases of aseptic meningitis and acute encephalitis with no known cause occur with greater
frequency in the summer months and in those younger than 1 year of age.
40
Figure 20. Aseptic meningitis and encephalitis, unknown etiology incidence rate per 100,000, by
county, Illinois, 2001
41
Haemophilus influenzae (invasive disease)
Background
Haemophilus influenzae can cause invasive disease such as meningitis, septic arthritis,
pneumonia, epiglottitis and bacteremia. It is transmitted by droplets and discharges from the nose
and throat. The incubation period is probably short, from two to four days. If the household of a
case includes an infant younger than 12 months of age, regardless of vaccination status, or a child
between 1 and 3 years of age who is not fully vaccinated, then all household contacts should be
given an antibiotic effective in eliminating carriage of the organism. Children younger than 5
years of age should be vaccinated against H. influenzae. In the United States, conjugate vaccines
against H. influenzae type b were introduced in 1987 and have resulted in a dramatic drop in
cases.
Between 10 percent and 100 percent of healthy children may carry H. influenzae in the
nasopharynx. From 75 percent to 95 percent of the strains carried may be non-typable or
unencapsulated.
CDC has identified that serotyping of H. influenzae by slide agglutination in state
laboratories can be inaccurate. In a CDC study, 70 percent of 40 H. influenzae isolates reported as
serotype b by state laboratories were actually identified as nontypable at CDC.
Case definition
The case definition for a confirmed case of invasive H. influenzae in Illinois is a clinically
compatible illness with isolation of the organism from a normally sterile site. A probable case is a
clinically compatible illness and detection of H. influenzae type b antigen in CSF.
Descriptive epidemiology
•
•
•
•
•
•
•
•
Number of cases reported in Illinois in 2001 – 103 (five-year median = 62). From 1996 to
2001, the number of cases reported per year ranged from 42 to 103 (Figure 25).
Age – 58 percent of the cases were older than 49 years of age (Figure 26). None of the
reported cases due to H. influenzae type b were younger than 5 years of age; all were from
52 to 82 years of age. Therefore, there were no vaccine preventable cases of invasive H.
influenzae during 2001.
Gender – 58 percent of cases were in females.
Race/ethnicity – 11 percent were African American, 4 percent were Asian, 84 percent were
white and 5 percent were other races; 12 percent were Hispanic.
Presentation – 76 percent had bacteremia, 19 percent had pneumonia, 10 percent had
meningitis, 1 percent had peritonitis and 1 percent had cellulitis. (Some individuals had
more than one manifestation of disease and were counted in each manifestation.)
Treatment – 95 of 96 reported cases for which information was available were
hospitalized.
Mortality – 23 percent of 61 cases where information was available died. Twelve of the 14
fatal cases occurred in individuals older than 50 years of age.
Diagnosis – All but one case was culture confirmed. H. influenzae was isolated from blood
(84 cases), CSF (9 cases), pleural fluid (3 cases), peritoneal fluid (1 case) and from other
or unknown sites (7 cases). Typing was attempted on specimens from 69 percent of
reported cases; 4 percent of the isolates for which typing was attempted were type b, 18
42
percent were type f and 11 percent were type e. Sixty-six percent of cases were nontypable.
Summary
While the reported cases of H. influenzae in Illinois have decreased dramatically since the
introduction of an effective vaccine, the number of cases increased in 2001. Of the isolates that
were typed, only 4 percent were type b and none of these cases were age 0-5 years for whom the
vaccine is indicated. This is down from 18 percent typed as b in 2000. More than half (58
percent) of all cases occurred in people older than 49 years of age.
Suggested readings
MMWR. Summary of notifiable diseases-United States, 2001. MMWR
2003;50(53):p.xiv.
43
Listeriosis
Background
Listeriosis is caused by infection with Listeria monocytogenes. L. monocytogenes is
common in the environment. Listeriosis is a foodborne illness that can cause sepsis in the
immunocompromised and meningoencephalitis and febrile gastroenteritis in immunocompetent
persons. Listeriosis has the highest case fatality rate of any foodborne illness. In a study in Israel,
higher mortality rates have been associated with older age, presence of CNS infection and
immunodeficiency. Pregnant women whose gastrointestinal tracts become colonized with the
bacteria after they eat contaminated foods can transmit the organism to the fetus or can
contaminate the baby’s skin or respiratory tract during childbirth.
The median incubation period is three weeks, which makes identifying a suspect food
vehicle difficult. L. monocytogenes is found frequently in nature and can be cultured from foods
and the environment, which makes typing of isolates from patients and suspected food items
important. The majority of isolates are ½ a, ½ b or 4b. Pulse field gel electrophoresis can be used
to further discriminate between isolates. Contaminated food vehicles often identified in outbreaks
of listeriosis include unpasteurized dairy products. However, other vehicles have been identified.
Of the 10 diseases/syndromes under active FoodNet surveillance (those caused by
Campylobacter, Cryptosporidium, Cyclospora, E. coli O157:H7, HUS, Listeria monocytogenes,
Salmonella, Shigella, Vibrio and Yersinia enterocolitica), listeriosis comprised 0.7 percent of the
reported infections in data from 2001.
Case definition
Illinois uses the CDC case definition for the reporting of Listeria cases: a clinically
compatible history (stillbirth, listeriosis of the newborn, meningitis, bacteremia or localized
infection) and isolation of L. monocytogenes from a normally sterile site. In the setting of
miscarriage or stillbirth, isolation of L. monocytogenes from placental or fetal tissue is adequate as
laboratory confirmation. A maternal-child pair should only be counted as one maternal case.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 24 total (none were described as cases of
meningitis) (five-year median = 23) (Figure 27). The 2001 incidence for all reported
listeriosis was 0.2 per 100,000 population.
•
Age – Cases ranged in age from 2 years to 98 years of age; 65 percent of cases were older
than 59 years of age.
•
Gender – Overall, 50 percent of the listeriosis cases were in females.
•
Race/ethnicity – 85 percent were white, 10 percent were African American and 5 percent
were Asian; none reported Hispanic ethnicity.
•
Diagnosis – For reported cases not involving pregnancy, the site of Listeria isolation was
identified as follows: blood (12), other sites (2) and cerebrospinal fluid (0).
•
Underlying conditions – Two pregnant women were reported with listeriosis. One
pregnancy resulted in a normal live birth and, for one case, the pregnancy outcome was
unknown. For 15 of the other cases, information was available on underlying conditions
and all but four had an existing immunosuppressive condition. Four of these 15 cases had
hematologic malignancies.
•
Mortality – Among the 14 cases with information on mortality, four died. Underlying
44
medical conditions were noted in two of the fatal cases.
Summary
In 2001, 24 listeriosis cases were reported to IDPH ; 65 percent of the cases were older
than 59 years of age.
Suggested readings
Siegman-Igra, et al. Listeria monocytogenes infection in Israel and review of cases
worldwide. Emerg Inf Dis 2002; 8(3): 305-10.
45
Neisseria meningitidis, Invasive
Background
The bacteria that causes meningococcal disease, N. meningitidis, is carried in the pharynx
by about 5 percent to 10 percent of the population. The most common serogroups identified in
human infection include A, B, C, W135 and Y. The organism is transmitted by direct contact with
respiratory droplets from the nose and throat of an infected person. Most patients acquired
infection from an asymptomatic carrier during face-to-face contact including coughing, sneezing
and kissing and the sharing of drinks, foods and cigarettes. The incubation period ranges from two
to 10 days and is usually three to four days. Meningococcal disease is an acute bacterial disease
that may be characterized by fever, headache, stiff neck, delirium and, often, a rash and vomiting.
Meningococcal disease presents as meningitis in 80 percent to 85 percent of cases. Septicemia
also can result from infection with N. meningitidis. The overall case fatality rate is between 5
percent and 10 percent. Carriage of the meningococcus organism is transient and the level of
carriage does not predict the course of an outbreak. Less than 1 percent of exposed persons who
become infected develop invasive disease.
Antimicrobial chemoprophylaxis is used for close contacts of cases. Only close contacts
should be given chemoprophylaxis due to concerns about antimicrobial resistance. Vaccination
can be used as an adjunct measure to protect against A, C, Y and W135 serogroups. In 1997, the
American College Health Association recommended that college students consider meningococcal
disease vaccination. A CDC study in the United States of 50 college students found that freshmen
living in dormitories had an elevated risk of meningococcal disease as compared to other college
students. The incidence for freshman in dormitories was five per 100,000.
Two cases in the United States in 2000 were attributed to transmission to microbiologists
in laboratories. N. meningitidis is classified as a biosafety level 2 organism. Guidelines
recommend use of a biosafety cabinet for mechanical manipulation of samples with a substantial
risk for droplet formation. Use of a biosafety cabinet during manipulation of sterile site isolates of
N. meningitidis would ensure protection.
During the Hajj pilgrimage season in 2000 an increase in N. meningitidis serogroup W135
was reported among pilgrims. Only 1 percent to 2 percent of cases were secondary cases.
International travelers are at risk of acquiring N. meningitidis during travel. Vaccine may be
advisable for pilgrims to the Hajj.
In a study in Germany, during an outbreak, there was a nine-fold increase in risk
associated with visiting discotheques. An association with visiting discotheques and bars has
been reported in several other published outbreaks and may be related to crowded conditions,
sharing of drinks, and other behaviors in this social setting.
In 2001, 2,333 cases were reported in the United States. Eighty-three percent were
confirmed and 4 percent were probable. Serogroup information was only reported for 33 percent
of isolates and approximately one-third of cases were serogroup Y and one-third were serogroup
B. Serogroup C comprised 27 percent of isolates.
Vaccination has been effective in decreasing N. meningitidis in military recruits.
Incidence rates of disease dropped from 24 per 100,000 person-years before vaccination to 3.5
cases per 100,000 person-years when vaccine was routinely used.
Case definition
The case definition for a confirmed case of meningococcal disease is a clinically
compatible case from whom N. meningitidis is isolated from a normally sterile site. The case
46
definition for a probable case is a compatible illness with positive results on latex agglutination,
or gram-negative diplococci in CSF. A person without laboratory confirmation of N. meningitidis
but with a clinical diagnosis of rash illness consistent with meningococcemia will be counted as a
case in Illinois.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 88 (incidence of 0.7 per 100,000) (five-year
median = 111) (Figure 28). Six cases were reported to be in college students; two cases
were reported in day care attendees. No clusters requiring vaccination campaigns occurred
in 2001.
•
Age – Median age was 22. Fatal cases ranged from 1 month to 97 years of age. The age
distribution of meningococcal disease is shown in Figure 29.
•
Gender – 47 percent were female.
•
Race/ethnicity – 15 percent were African American, 83 percent were white and 2 percent
were Asian; 5 percent were Hispanic.
•
Season peak – Meningococcal disease occurred throughout the year (Figure 30).
•
Presentation – Case reports indicated that 57 percent of reported cases had bacteremia, 45
percent had meningitis and 9 percent had pneumonia.
•
Diagnosis – 82 cases were culture confirmed, one was positive by latex agglutination, two
were clinical diagnoses of meningococcemia and three were an unknown method.
Serogrouping was performed on isolates from 73 percent of cases. In cases where typing
was done, serogroups were Y (37 percent), C (30 percent), B (22 percent), W-135 (5
percent) and nontypable (6 percent). Serogroup Y isolates have increased from 4 percent
of isolates in 1991 to 37 percent of isolates in 2001 (Figure 31).
•
Mortality – The case fatality rate was 27 percent for patients where outcome of infection
was known.
Summary
The number of N. meningitidis cases reported in Illinois in 2001 was lower than the fiveyear median. No vaccination campaigns were required in 2001. Illinois had a higher percent of
serogroup typing :73 percent compared to 33 percent nationwide.
Suggested readings
Bruce MG et al. Risk factors for meningococcal disease in college students. JAMA
2001;286(6):688-93.
Brundage JF et al. Meningococcal disease among United States military service members
in relation to routine uses of vaccines with two different serogroup-specific components, 19641998. CID 2002;1376-81.
Harrison LH et al. Invasive meningococcal disease in adolescents and young adults.
JAMA 2001;286(6):694-9.
Hauri AM et al. Serogroup C meningococcal disease outbreak associated with
discotheque attendance during carnival. Epi Inf 2000: 124:69-73.
Mayer LW et al. Outbreak of W-135 meningococcal disease in 2000; Not emergence of a
new W135 strain but clonal expansion within the electrophoretic type-37 complex. JID
2002;185:1596-605.
Memish ZA. Meningococcal disease and travel. CID 2002;34:84-90.
MMWR. Summary of notifiable diseases-United States, 2001. MMWR 2003;50(53):xix.
47
MMWR. Laboratory-acquired meningococcal disease-United States 2000. MMWR
2002;51(7):141-44.
48
49
Streptococcus pneumoniae, Invasive
Background
S. pneumoniae is the most common cause of meningitis, community-acquired pneumonia
and bacteremia, and acute otitis media. Pneumococci colonize the nasopharynx of 15 percent to
60 percent of individuals; most remain asymptomatic. Carriage is higher in children attending
child care centers outside the home. The onset of S. pneumoniae meningitis is usually sudden with
high fever, lethargy and signs of meningeal irritation. It is a sporadic disease in the elderly and in
young infants.
Antimicrobial susceptibility patterns are important in therapy and monitoring of
antimicrobial resistance. In 2001, in the CDC’s ABC Surveillance states, 10 percent of S.
pneumoniae isolates had interim resistance to penicillin (MIC 0.1-1 ug/mo), 16 percent were fully
resistant (MIC>2 ug/ml) and 19 percent were resistant to erythromycin. In addition, 10 percent of
isolates had intermediate resistance and 6 percent were fully resistant to cefotaxime. A study in
Baltimore showed that white race, suburban residence and winter respiratory season were found to
be predictors of infection with penicillin-resistant Streptococcus pneumoniae as compared to non
penicillin resistant S. pneumoniae.
In 2001, invasive S. pneumoniae in children younger than 5 years of age was reportable in
28 states. The incidence rate was 13 per 100,000 in 11 states that actually reported, which is lower
than the 40 per 100,000 in CDC’s ABC surveillance program.
The pneumococcal conjugate 7-valent vaccine (6B, 14, 18C, 19F, 23F, 9V, 4) was licensed
in the United States in February 2000 and can be used in children younger than 2 years of age. The
vaccine protects against the seven strains of pneumococcus that cause 80 percent of the invasive
disease among children in the United States. In one study in Finland, a 34 percent reduction in the
incidence of pneumococcal acute otitis media occurred as a result of vaccination with a conjugate
vaccine. Beginning in August 2001, supplies of this vaccine became limited.
The Advisory Committee on Immunization Practices recommends that vaccine be given
to infants in a series of four injections (at 2, 4, 6 and 12-15 months of age). The recommendation
applies to all children younger than 24 months of age and to children 24-59 months of age who
are at higher risk of infection, including those with certain illnesses (e.g., sickle cell anemia, HIV,
chronic heart or lung disease) and those who are Alaska natives, American Indian or African
American. The vaccine also can be considered for other children ages 24 to 59 months who are at
increased risk, such as children in group day care, those with frequent otitis media or those who
are economically or socially disadvantaged.
A study examining pneumococcal vaccination status in adults using the Behavioral Risk
Factor Surveillance System (BRFSS) showed that 57 percent of those older than 64 years of age
in Illinois reported vaccination during the previous year.
Several studies involving S. pneumoniae were conducted in Illinois. In a study of S.
pneumoniae reporting from laboratories from April 2001 to March 2002 in Illinois, only 43
percent of all invasive S. pneumoniae were reported. However, reporters were notified in midJuly that all invasive S. pneumoniae were reportable so for the first half of the year only
meningitis due to S. pneumoniae was reported. Sixty-three percent of laboratories in Illinois
performed susceptibility testing on S. pneumoniae isolates for all three antibiotics (penicillin,
vancomycin, cefotaxime/ceftriaxone) as recommended by the National Committee for Clinical
Laboratory Standards.
Another study of 642 invasive S. pneumoniae cases reported in Illinois between April
2001 and March 2002 showed that three-quarters of cases survived. The most common types of
50
disease reported were bacteremia (95 percent) and pneumonia (53 percent). The most common
underlying conditions were chronic cardiovascular (26 percent) and chronic pulmonary disease
(22 percent). Antibiotic non-susceptibility rate was highest for penicillin (25 percent of 255 cases
tested).
Starting on April 1, 2001, all forms of invasive S. pneumoniae became reportable. In
addition, reporting of antibiotic resistance for this pathogen was put into place. In previous years,
only meningitis due to S. pneumoniae was reportable.
Case definition
A case is defined as a person with clinically compatible symptoms and from whom
isolation of the organism from a normally sterile site has occurred.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 491 (Figure 32). The incidence rate for
2001 was four per 100,000.
•
Age – Mean age of cases was 49 (see Figure 33 for age distribution).
•
Gender – 51 percent were female.
•
Race/ethnicity – 17 percent were African American and 79 percent were white; 6 percent
were Hispanic.
•
Seasonal peak – The majority of cases occurred in the winter and spring months (Figure
34). In April, the change in reporting requirements went into effect.
•
Diagnosis – The most common types of disease reported were bacteremia (94 percent) and
pneumonia (53 percent). Individuals may have reported multiple types of disease.
•
Underlying conditions – The most common underlying conditions for invasive
pneumococcal disease was chronic cardiovascular and chronic pulmonary disease.
•
Mortality – The case fatality rate was 11 percent for cases where outcome was known.
Summary
In previous years, only S. pneumoniae meningitis was reportable. Beginning on April 1,
2001, all invasive S. pneumoniae became reportable resulting in a large increase in the number of
reported cases. The age distribution changed dramatically compared to 2000, with an increase in
cases older than 59 years of age in 2001 when all invasive S. pneumoniae cases became reportable
mid-year.
Suggested readings
Albanese BA, Roche JC et al. Geographic, demographic, and seasonal differences in
penicillin-resistant Streptococcus pneumoniae in Baltimore. Clin Inf dis 2002;34:15-21.
Giebink GS. The prevention of pneumococcal disease in children. NEJM
2001;345(16):1177-83.
MMWR. Summary of notifiable diseases-United States, 2001. MMWR 2003; 50(53):o.
xxi-xxii.
MMWR. Influenza and pneumococcal vaccination levels among persons aged > 65 yearsUnited States 2001. MMWR 2002; 51(45): 1019-1023.
51
52
Invasive group B Streptococcus
Background
Group B streptococcus (GBS) and E. coli cause most cases of sepsis in infants. Around 10
percent to 35 percent of pregnant women may be colonized with GBS at the time of labor placing
them at risk for transmitting the disease to their infants.
GBS infections are due to Streptococcus agalactiae and cause disease and death in
newborns and morbidity in peripartum women and nonpregnant adults with chronic medical
conditions. Early-onset disease of neonates (<7 days) may consist of sepsis, respiratory distress,
apnea, shock, pneumonia and meningitis. The infection is acquired during delivery or in utero.
Early onset disease is caused by maternal GBS carriage. Risk factors for early onset GBS sepsis
(that occurs within 72 hours of life) include fever in the mother during labor, preterm delivery,
membrane rupture greater than 18 hours before delivery and a mother with a previous infant with
GBS. Infants acquire infection through aspiration of contaminated amniotic fluid or during
passage through the birth canal. Late onset disease (7 days to several months of age) is
characterized by sepsis and meningitis and is acquired by person-to-person contact. Only about 50
percent of late onset disease cases have been shown to be of maternal origin.
In 1996, consensus guidelines recommended one of two approaches for prevention of
neonatal GBS disease. One approach was risk-based and the other was screening-based.
Intrapartum antibiotic prophylaxis is recommended for women at increased risk. When mothers
receive intrapartum antibiotics the risk of GBS sepsis is decreased by two-thirds. One study
conducted by CDC found that the screening-based approach prevented more cases of GBS than
the risk-based approach.
Beginning on April 1, 2001, only invasive GBS in infants younger than 3 months became
reportable in Illinois. Previously, invasive GBS in all ages was reportable.
Case definition
A confirmed case of invasive GBS disease is defined as isolation of GBS from a normally
sterile site (e.g., blood or cerebrospinal fluid). A probable case is defined as a person who is latex
agglutination positive for GBS from a sterile site.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 65 (five-year median = 32) (see Figure 35).
•
Age – 61 percent occurred in those younger than 1 year of age compared to 35 percent in
2000 when there was required reporting of all invasive group B streptococcus (Figure 36).
•
Gender – 51 percent were female.
•
Race/ethnicity – 61 percent were white and 36 percent were African American; 11 percent
were Hispanic.
•
Seasonal variation – Cases occurred throughout the year (Figure 37).
•
Case outcome - Two cases were fatal; both cases were older than 59 years of age.
Summary
Cases of GBS disease in newborns may be preventable if the appropriate guidelines are
followed by health care providers. The number of cases of invasive GBS in Illinois in 2001
increased in comparison to previous years probably due to informational material sent to health
care providers and laboratories about new reporting requirements. The percentage of cases in
53
those younger than 1 year of age increased from 35 percent to 61 percent from 2000 to 2001. This
is likely due to the reporting change that only required reporting of invasive GBS in children
younger than 3 months of age beginning on April 1, 2001. The introduction of this modified
surveillance system may have stimulated reporting of these cases.
Suggested readings
Eschenbach DA. Prevention of neonatal Group B streptococcal infection. NEJM
2002;347(4):280-81.
Schrag SJ, Zell ER et al. A population-based comparison of strategies to prevent earlyonset group B streptococcal disease in neonates. NEJM 2002; 347(4): 233-9.
Schuchat A. Group B streptococcal disease: From trials and tribulations to triumph and
trepidation. Clin Inf Dis 2001;33:751-6.
54
55
Cryptosporidiosis
Background
Cryptosporidiosis is primarily a gastrointestinal disease that results from infection with
Cryptosporidium species oocysts. Because of a lack of host specificity, Cryptosporidium parvum
infects a wide range of mammalian species. Two genotypes of C. parvum are known to infect
humans including human type 1 and bovine type 2. Oocysts are immediately infective upon
excretion by an infected host and can be shed for up to two weeks or longer in immunocompetent
humans. Infection is spread through person-to-person transmission, from direct contact with
animals and by swimming in contaminated water. Approximately 1 percent to 3 percent of the
general population may be excreting oocysts. The incubation period is an average of seven days
(range is one to 12 days). Cryptosporidium produces a self-limited diarrhea in immunocompetent
persons and a potentially life-threatening diarrhea in the immunocompromised. The duration and
severity of symptoms depends on the immune status of the person. In immunocompetent persons,
asymptomatic infections, acute diarrhea or persistent diarrhea may occur as a result of
Cryptosporidium infection. Diarrhea can last two weeks and vomiting or fever may be present in
more than half of infected persons.
Oocysts of cryptosporidia can be found in many types of water including untreated surface
water, filtered swimming pool water and even chlorine-treated or filtered drinking water. The
minimum level of detectable oocysts that pose a public health threat in domestic water supplies is
not known. Outbreaks associated with water supplies can occur when there is fecal contamination
of drinking water.
Of the 10 diseases under active surveillance in FoodNet sites (illnesses caused by
Campylobacter, Cryptosporidium, Cyclospora, E. coli O157:H7, HUS, Listeria monocytogenes,
Salmonella, Shigella, Vibrio and Yersinia enterocolitica), Cryptosporidium comprised 4 percent
of the reported infections in data from 2001. Data from 2001 showed the incidence rate per
100,000 for Cryptosporidium ranged from 0.5 to 4 at the nine FoodNet sites.
Important features of cryptosporidiosis include the following: 1) water-borne outbreaks are
typical, 2) oocysts are resistant to commonly used disinfectants 3) transmission can occur by
direct fecal-oral contact, 4) as few as 10 to 100 oocysts can cause infection, 5) oocysts are
infectious upon excretion and 6) asymptomatic infections occur. Molecular typing techniques are
beginning to be used in countries such as Ireland and England during outbreaks.
Case definition
A confirmed case of cryptosporidiosis in Illinois is a laboratory-confirmed case
(demonstration of Cryptosporidium oocysts in stool, or demonstration of Cryptosporidium in
intestinal fluid or small bowel biopsy specimens, or demonstration of Cryptosporidium antigen in
stool by a specific immunodiagnostic test such as ELISA) associated with diarrhea and one or
more of the following symptoms: abdominal cramps, loss of appetite, low-grade fever, nausea or
vomiting.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 483; 125 were non-outbreak related cases
(five-year median = 90) (Figure 38). The incidence rate was 4 per 100,000.
An outbreak of cryptosporidiosis in 2001 in Tazewell County resulted in a large increase
of cases compared to previous years. See the food and water borne section for a
56
description of the outbreak.
•
Age – Mean age for all 2001 cases was 18. Age distribution of cases is shown in
Figure 39.
•
Gender – 51 percent were male.
•
Race/ethnicity – 89 percent were white, 10 percent were African American and 1
percent were other races; 6 percent were Hispanic. The proportion of African
Americans with cryptosporidiosis (10 percent) was lower than their proportion in
the Illinois population (15 percent).
•
Seasonal variation – Cases peaked in August (Figure 40), which was due to the
large outbreak in Tazewell County.
Summary
The number of reported cases of cryptosporidiosis in 2001 was 483. A large outbreak at a
municipal water park in Tazewell County accounts for most (74 percent) of the cases in 2001. The
mean age of all cases was 18 years, while the mean age of those associated with the outbreak was
9 years. Due to the outbreak, there was a peak in cases in August.
Suggested readings
Causer L et al. Recreational water outbreak of cryptosporidiosis parvum-Illinois, August
2001. Infectious Disease Society of America meeting 2003. (abstract). Chicago, Illinois.
Chen, X-M, Keithly JS et al. Cryptosporidiosis. NEJM 2002;346(22):1723-31.
Glaberman S, Moore JE et al. Three drinking-water-associated cryptosporidiosis
outbreaks, Northern Ireland. Emerging Inf Dis 2002;631-4.
Howe AD, Forster S et al. Cryptosporidium oocysts in a water supply associated with a
cryptosporidiosis outbreak. Emerging Inf Dis 2002;8(6): 619-24.
MMWR. Preliminary FoodNet Data on the incidence of foodborne ilnesses-selected sites,
United States, 2001. MMWR 2002;51(15):325-9.
57
58
Cyclosporiasis
Background
Cyclosporiasis is caused by a protozoal organism, Cyclospora cayatensis. Clinical illness
consists of watery diarrhea and abdominal cramping. Diarrhea is usually self-limiting but may be
prolonged. The median incubation period is seven days. Transmission to persons is usually
through drinking or swimming in contaminated water. Several international outbreaks have
involved consumption of raspberries from Guatemala. Basil and lettuce also have been implicated
in transmission. Reporting of cyclosporiasis became mandatory on April 1, 2001, in Illinois.
Case definition
Laboratory confirmation is the finding of C. cayatensis oocysts in stool by microscopic
examination or in intestinal fluid or small bowel biopsy specimens; or demonstration of
sporulation or PCR positive in stool, duodenal/jejunal aspirates or small bowel biopsy specimens.
CDC has two case classifications:
Confirmed, symptomatic - laboratory confirmed with clinically compatible illness
Confirmed, asymptomatic - laboratory confirmed with no symptoms
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 - 2.
•
Age – The ages of the two cases were 3 years of age and 28 years of age.
•
Gender – Both cases were female.
•
Race/ethnicity – Both cases were white and non-Hispanic.
•
Seasonal variation – One case had onset in May and one in November.
•
Travel – One case traveled to Mexico prior to onset. The travel history of the other case
was unknown.
Summary
Cyclospora became reportable on April 1, 2001. Two cases were reported in Illinois
residents in 2001. One case had traveled to Mexico prior to onset, the travel history of the other
was unknown.
59
Ehrlichiosis
Background
Ehrlichia are bacteria that infect a wide variety of animals and are transmitted by tick
bites. Three Ehrlichia pathogens have been identified in the United States: E. chaffeensis (causing
human monocytic ehrlichiosis (HME)), Anaplasma phagocytophilum (causing human
granulocytic ehrlichiosis (HGE)) and E. ewingii (causing mainly canine disease but some human
HGE). Both HGE and HME are zoonotic diseases requiring an arthropod vector and a mammalian
reservoir. Differences in the geographic distribution of the tick vectors result in HME occurring
primarily in the southern and southeastern United States and HGE in the northeast and northern
Midwest. In animal studies, ehrlichiosis could be transmitted within the first 24 hours a tick is
attached. The incubation period is seven to 21 days.
HGE has been reported in the eastern and central United States and can be transmitted by
deer ticks. This is the same tick that transmits Lyme disease and human babesiosis, in these areas.
The primary reservoir host mammals for HGE are thought to be the white-footed mouse and the
white-tailed deer. A study in northwestern Wisconsin from 1997 through 1999, found the annual
incidence of HGE was nine per 100,000 in the area. Three-quarters of the cases were identified
from May through July. The incidence of HGE increased with age. Approximately 13 percent of
persons with febrile illnesses studied in the northwestern part of Wisconsin were positive for
HGE.
The majority of the ehrlichiosis cases in the United States are HME. E. chaffeensis is
carried by the lone star tick (Amblyomma americanum) in the south, central and southeastern parts
of the country.
Both HME and HGE result in similar symptoms: fever, headache and myalgia. Cases also
may have low platelets, low white blood cells and increased liver enzymes. A rash may be present
in approximately one-third of HME cases; rashes are much less common in HGE. These Ehrlichia
organisms can form clusters of organisms, called morulae, in the white blood cells. The case
fatality rate has been reported as 5 percent in HME and 10 percent in HGE.
Mandatory reporting of ehrlichiosis in Illinois began on April 1, 2001.
Case definition
A confirmed case of ehrlichiosis is defined as a clinically compatible case that is
laboratory confirmed. Laboratory confirmation is by a four-fold or greater change in antibody titer
to Ehrlichia species by immunofluorescence test (IFA) in acute and convalescent specimens or
positive by polymerase chain reaction or intracytoplasmic morulae identified in blood, bone
marrow or cerebrospinal fluid (CSF) leukocytes and an IFA antibody titer of greater than or equal
to 64. A probable case is a clinically compatible case with either a single IFA antibody serologic
titer of >1:64 or intracytoplasmic morulae identified in blood, bone marrow or CSF leukocytes.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 7 (3 HME and 1 HGE; 3 were of unknown
type).
•
Age – Cases ranged in age from 45 to 70 years of age.
•
Gender – Six cases were male.
•
Race/ethnicity – All cases were white; none were Hispanic.
•
Geographic distribution – Sites of tick exposure for the cases were Clay County (1),
Jefferson County (1), Pope County (1) and Randolph County (1). Two individuals
60
•
•
•
reported traveling to Shawnee National Forest in southern Illinois and one reported
traveling to Kentucky within 30 days of onset of symptoms.
Seasonal variation – Onsets of the seven cases occurred between April and July.
Outcomes – Five cases were hospitalized. One case was fatal.
Past incidence – Reporting of ehrlichiosis was voluntary prior to 2001. Reported cases of
ehrlichiosis in Illinois in past years have been infrequent and increased in 2001: 1991 (0),
1992 (0), 1993 (0), 1994 (1), 1995 (4), 1996 (4), 1997 (0), 1998 (2), 1999 (5), 2000 (1)
and 2001 (7).
Summary
The initiation of mandatory reporting of ehrlichiosis in 2001 coincided with an increase in
the number of cases reported. Most Illinois tick exposures related to ehrlichiosis cases have been
in southern Illinois.
Suggested readings
Belongia EA, Gale CM et al. Population-based incidence of human granulocytic
ehrlichiosis in northwestern Wisconsin, 1997-1999. JID 2001;184:1470-4.
Belongia EA, Reed KD et al. Tickborne infections as a cause of nonspecific febrile illness
in Wisconsin. CID 2001;32:2434-9.
Lantos P, Krause PJ. Ehrlichiosis in children. Sem Ped Inf Dis 2002;13(4):249-56.
61
Enteric Escherichia coli infections (E. coli O157:H7 and other
enterohemorrhagic E. coli, enterotoxigenic E. coli, enteropathogenic E. coli)
Background
Escherichia coli O157:H7 causes a diarrheal illness. The infectious dose is thought to be
low due to evidence of person-to-person transmission and recreational water exposure
transmission. The incubation period is from three to eight days with an average of three to four
days. Occasionally, longer incubation periods have been reported. Infection with E. coli O157:H7
produces symptoms that range from mild to bloody diarrhea and that may progress to hemolytic
uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP).
E. coli O157:H7 is transmitted through consumption of contaminated food or beverage,
person-to-person contact or swimming in contaminated recreational water. Although undercooked
ground beef is a primary source for E. coli O157:H7 infections, outbreaks have been associated
with other foods, including alfalfa sprouts. E. coli O157:H7 infection has been linked in one case
to consumption of venison. In addition, outbreaks have been associated with drinking water. An
outbreak in Wyoming was linked to drinking of unchlorinated municipal water. The organism has
been cultured from approximately one-quarter of cattle slaughtered in the Midwest. A study in
Canada identified that human shiga toxin producing STEC infections were associated with the
ratio of beef cattle to human population and the application of manure to the surface of
agricultural land by a solid spreader and by a liquid spreader.
Outbreaks of E. coli O157:H7 have occurred in visitors to dairy farms and petting zoos. In
one outbreak in Pennsylvania, contact with calves and their environment was associated with an
increased risk of disease and handwashing was protective against infection. An outbreak in Ohio
in 23 persons was due to exposure to a building holding contaminated sawdust. An outbreak of E.
coli O157:H7 in Scotland in 1996 resulted in 345 cases. Thirty-four cases developed HUS and 16
died. HUS developed from three to 15 days following diarrheal illness. In this study, risk factors
for HUS were age younger than 15 years and age older than 65 years. Administration of
antibiotics prior to symptoms also was associated with HUS in this study. Outbreaks of non O157
STEC have been identified. In Germany in 2000, an outbreak of E. coli O26:H11 was linked to
beef consumption.
Of the 10 diseases under active surveillance in the FoodNet sites (illnesses caused by
Campylobacter, Cryptosporidium, Cyclospora, E. coli O157:H7, HUS, Listeria monocytogenes,
Salmonella, Shigella, Vibrio and Yersinia enterocolitica), E. coli O157:H7 was responsible for 4
percent of the reported infections in 2001 data. The incidence rate for E. coli O157:H7 ranged
from 0.4 to 4.7 per 100,000 at the nine FoodNet sites.
CDC recommends that all bloody diarrheal stools be routinely cultured for E. coli
O157:H7. Rapid tests also are available to directly detect shiga toxin in stool specimens.
Specimens testing positive should be cultured to identify which organism (E. coli or Shigella)
produced the shiga toxin. Shiga toxin producing E. coli should be forwarded to the IDPH
laboratory for possible subtyping.
Enterotoxigenic E. coli is considered to be a common cause of traveler’s diarrhea. U.S.
residents who travel overseas may return home with it.
Reporting for enteric E. coli infections in Illinois was expanded in April 2001 to include
enteric E. coli infections in addition to E. coli O157:H7 infections. Other enterohemorrhagic E.
coli (other than O157), enterotoxigenic E. coli (ETEC) and enteropathogenic E. coli became
reportable under this category.
62
Prevention for enteric E. coli infections include cooking food thoroughly, promptly
refrigerating foods and separating cooked and raw foods. Antibiotics are contraindicated for
treatment of E. coli O157:H7 infections because such treatment can lead to release of toxin as
bacteria die, thereby increasing the risk for development of HUS.
Case definition
The case definition for a confirmed case of E. coli O157:H7 in Illinois is a person with
isolation of E. coli O157:H7 from a stool specimen or E. coli O157 organisms that are laboratory
confirmed as producing shiga toxin. E. coli isolates from stool from a person that produce shiga
toxin but are not identified as O157 are also reportable as enterohemorrhagic E. coli, non O157. A
confirmed case of ETEC is a person with laboratory confirmation of enterotoxigenic E. coli from
stool. A confirmed case of enteropathogenic E. coli is a clinically compatible illness with
laboratory confirmation of enteropathogenic E. coli from stool. A probable case of ETEC,
enteropathogenic E. coli, or other enterohemorrhagic E. coli is a person who is epidemiologically
linked to cases but has not been laboratory confirmed.
Descriptive epidemiology
E. coli O157:H7
•
Number of cases reported in Illinois in 2001 – 173 (five-year median = 194) (Figure 41).
The large number of cases in 1999 (498) was primarily due to one outbreak in Menard
County. The incidence in 2001 was 1.4 cases per 100,000 population, which is within the
range of what was found in CDC’s FoodNet sites (0.4 to 4.8 per 100,000).
•
Age – Cases occurred in all age groups with very few in those younger than 1 year of age
(median = 15 years of age) (Figure 42).
•
Gender – 46 percent were female.
•
Race/ethnicity – 97 percent were white and 3 percent were African American; 6 percent
were Hispanic.
•
Season variation – The largest number of cases were reported in the summer from July to
September (57 percent of cases) (Figure 43).
•
Symptoms – Among those with culture-confirmed E. coli O157:H7 for which symptom
information was available, 99 percent reported diarrhea, 97 percent reported abdominal
cramps, 89 percent reported bloody diarrhea, and 44 percent reported fever; 8 percent of
patients for whom information was available had hemolytic uremic syndrome (HUS) and 2
percent had thrombotic thrombocytopenic purpura (TTP).
•
Treatment – Of 170 patients for whom information was available, 57 percent were
hospitalized.
•
Mortality – Two cases were fatal; both were older than 64 years of age. Both fatalities had
HUS.
Risk factors for E. coli O157:H7
The standard case report form developed by CDC is used to investigate E. coli O157:H7
cases in Illinois. It includes questions on possible sources for E. coli O157:H7. Individuals are
asked if they consumed any ground beef and are then asked if they consumed undercooked ground
beef. Cases also are asked if they were around children with diapers or if they changed diapers.
The results of investigation of exposure to risk factors are presented in Table 4.
The following percentages of patients reported consuming foods that have been associated
with this infection in the seven days before symptom onset: ground beef (77 percent), other beef
63
products (28 percent), well water (21 percent), undercooked ground beef (16 percent), other
undercooked beef products (6 percent) and other unchlorinated water (6 percent); 11 percent
reported visiting or living on a farm. These risk factors were not confirmed as the source of illness
in these cases.
ETEC
Twenty-two cases of ETEC were reported in 2001. Twenty-one of 22 were related to an
outbreak in Sangamon County. See foodborne outbreak section for more information.
Other types of reportable enteric E. coli
None reported.
Summary
Most cases of E. coli O157:H7 occur in the summer months. Bloody diarrhea was reported
by 89 percent of individuals; 8 percent of patients reportedly had HUS. More than half the cases
were hospitalized; two cases were fatal. Almost 16 percent of cases reported consuming
undercooked ground beef. The majority of the ETEC cases reported were due to a single outbreak.
Note: CDC has 174 cases of E. coli O157:H7 recorded for Illinois in the “Summary of Notifiable
Diseases-United States, 2001", published on May 2, 2003; the correct number should be 173.
Suggested readings
Banatvala N et al. The United States national prospective hemolytic uremic syndrome
study: Microbiologic, serologic, clinical, and epidemiologic findings. JID 2001;183:1063-70.
Breuer T, Benkel DH et al. A multistate outbreak of Escherichia coli O157:H7 infections
linked to alfalfa sprouts grown from contaminated seeds. Emerg Inf Dis 2001:7(6):977-82.
Crump JA, Sulka AC et al. An outbreak of Escherichia coli O157:H7 infections among
visitors to a dairy farm. NEJM 2002;347:8:555-60.
Dundas S et al. The Central Scotland Escherichia coli O157:H7 outbreak: Risk factors for
the hemolytic uremic syndrome and death among hospitalized patients. CID 2001;33:923-31.
Grabowski EF. The hemolytic-uremic syndrome-toxin, thrombin and thrombosis. NEJM
2002;346(1):58-61.
Olson SJ, Miller G et al. A waterborne outbreak of Escherichia coli O157:H7 infections
and hemolytic uremic syndrome: Implications for rural water systems. Emerg Inf Dis
2002;8(4):370-75.
Rabatsky-Ehr T, Dingman D. et al.Deer meat as the source for a sporadic case of
Escherichia coli O157:H7 infection, Connecticut. Emerg Inf Dis 2002;8(5):525-8.
Safdar N, Said A, Gangnon RE, Maki DG. Risk of hemolytic uremic syndrome after
antibiotic treatment of Escherichia coli O157:H7 enteritis. A meta-analysis. JAMA
2002;288(8):996-1001.
Sanchez S, Lee MD, Harmon BG et al. Animal issues associated with Escherichia coli
O157:H7. JAVMA 2002;221(8):1122-25.
Valcour JE, Michel P, McEwen SA, Wilson JB. Associations between indicators of
livestock farming intensity and incidence of human shiga toxin-producing Escherichia coli
infection. Emerg Inf Dis 2002;8(3):252-7.
Varma JK et al. An outbreak of Escherichia coli O157 infection following exposure to a
contaminated building. JAMA 2003;290(20):2709-12.
64
Werber D, Fruth A et al. A multistate outbreak of shiga toxin-producing Escherichia coli
O26:H11 infections in Germany, detected by molecular subtyping surveillance. JID
2002;186:419-22.
65
66
Table 4. Reported characteristics of E. coli 0157:H7 cases in Illinois, 2001
# reporting
factor
Characteristic
Total # with
information on
factor
Percentage
reporting
characteristic
Attending or working in day care center
9
141
6
Attending or working at an institution
6
126
5
Employed as a health care worker
3
136
2
Employed as a food handler
3
133
2
Ground beef
98
128
77
Undercooked ground beef
20
127
16
Other beef products
35
126
28
8
124
6
Fast food
75
123
61
Other restaurant food
44
99
44
Well water
27
128
21
Other unchlorinated water
8
126
6
Apple cider
3
134
2
Raw milk
1
135
0.7
Contact with diapered child
Travel away from home
32
4
131
135
24
4
Swam
29
133
22
Contact with daycare child
18
130
14
Visit or live on farm
15
135
11
8
135
6
15
131
24
Food/water history in prior seven days
Undercooked other beef
Other factors in prior seven days
Contact with cattle or cattle manure
Changed diapers
Source: Illinois Department of Public Health, 2002
67
Foodborne and waterborne outbreaks
Background
Food can act as a vehicle for transmission of pathogens or their by-products. Although
many foodborne illnesses result in a few days of diarrhea – with additional symptoms such as
fever, vomiting or muscle aches – others can have serious health effects such as hemolytic
uremic syndrome, reactive arthritis, sepsis or Guillain Barré syndrome. The primary forms of
foodborne illness are intoxications, which are caused by toxins produced by organisms in the
food, and infections, where the organism must multiply in the person before causing illness.
Food borne illness can be caused by microorganisms and their toxins, marine organisms
and their toxins, fungi and chemical contaminants. There are four categories of organisms to
consider in discussing the causes of foodborne illness: viruses, bacteria, parasites and fungi. For
some viruses, such as hepatitis A or noroviruses (also known as small round-structured viruses)
humans are the only reservoir. Food can be contaminated with viruses if food handlers do not
practice good hygiene before preparing food that is not later cooked, or if sewage contaminates
the food. Rotaviruses can occasionally cause foodborne outbreaks. Shellfish have been associated
with hepatitis A virus, calicivirus and Vibrio spp. outbreaks.
Bacteria make up the largest category of foodborne agents. These include E. coli
O157:H7, Salmonella and Listeria monocytogenes. Parasites like Trichinella in pork, Anasakis in
raw fish or Cyclospora in raspberries also can cause foodborne illness. Some enteric pathogens,
such as Campylobacter, Giardia and Shigella, rarely cause foodborne outbreaks. Occasionally,
Listeria can cause febrile gastroenteritis. An outbreak of Listeria induced febrile gastroenteritis
in Los Angeles in 2001 was linked to consumption of precooked, sliced turkey. Listeriosis
outbreaks causing meningitis or causing pregnant women to have stillbirths or premature infants
can be associated with Mexican style cheese. In an outbreak in North Carolina in 2001, Mexican
cheese was made from unpasteurized milk and caused listeriosis. In 1994 in Illinois, an outbreak
of Listeria gastroenteritis from milk occurred in Jo Daviess county.
Although rarely reported, group A streptococcus (GAS) can cause foodborne outbreaks.
Incubation periods range from 32 to 52 hours. An unusual outbreak of foodborne group A
streptococcus occurring in a prison was reported from Australia in 1999. A foodhandler with
infected skin wounds was thought to have contaminated the food.
CDC published a surveillance summary for waterborne disease outbreaks reported in
1999 and 2000. Thirty-nine outbreaks were linked to drinking water, with 28 of these traced to
groundwater water sources. Fifty-nine outbreaks were linked to recreational water exposures.
Case definition
A foodborne outbreak is a cluster of illnesses in which two or more persons (usually
residing in separate households) experience the onset of a similar, acute illness (usually
gastrointestinal) following ingestion of common food or drink. CDC has established case
definitions for confirmed outbreaks and these are listed under the specific organisms in this
outbreak section.
For foodborne outbreaks, the number ill reflects those who meet a clinical case definition.
For outbreaks where the etiologic agent was suspected and not confirmed, and the clinical
68
syndrome matched the suspect etiologic agent but no laboratory confirmation was obtained, the
suspect cause is ascribed to this etiologic agent.
IDPH receives reports of potential foodborne outbreaks from many sources. Outbreak
investigations, which are conducted by local health departments, may not meet the case
definition for an outbreak and will not be counted in the state totals. There are a number of
factors that affect whether a cluster of illnesses is counted as a foodborne outbreak including lack
of information, classification as person-to-person transmission or failure of the symptoms and
incubation period to clearly indicate a known foodborne pathogen.
Descriptive epidemiology
Eighty-five possible food-or waterborne outbreaks were reported to IDPH by local health
departments (LDHs) during the 2001 calendar year. Of these, 10 were determined by the LHD or
by IDPH to not meet the criteria for a food-or waterborne outbreak. There were 75 outbreaks that
met the definition and were submitted to the CDC. Of these, the etiology was confirmed in 23
outbreaks, suspected in 41 outbreaks and determined to be unknown in 11 outbreaks.
In 2001, a total of 1,146 people were reported to have become ill as the result of the 74
food borne outbreaks and 358 as a result of one waterborne outbreak. The mean number ill per
foodborne outbreak was 15.5. There were no fatalities due to foodborne illness reported during
2001. Local health jurisdictions reporting outbreaks during 2001 were Cook (23), Chicago (14)
and Springfield (4). Coles, Madison, McHenry and St. Clair each reported three outbreaks.
Douglas, DuPage and Tazewell each reported two; and one each was reported from Adams,
Bureau, Champaign, Crawford, Effingham, Fulton, JoDaviess, Kane, Kendall, Lake, McLean,
Oak Park, Piatt, Winnebago, Woodford and multiple county health departments.
The 75 reported outbreaks occurred in the following months: January, five (7 percent);
February, three (4 percent); March, three (4 percent); April, eight (11 percent); May, 11 (15
percent); June, five (7 percent); July, 10 (13 percent); August, 9 (12 percent); September, 5 (7
percent); October, 7 (9 percent); November, one (1 percent); and December, eight (11 percent).
In the 75 outbreaks reported to CDC, the etiologic agent was determined to be bacterial,
either suspect or confirmed, in 35 (47 percent) (Table 5). The bacterial pathogens were as
follows: Clostridium perfringens/Bacillus cereus, 12 (34 percent); Salmonella spp. nine (26
percent); Staphylococcus aureus/Bacillus cereus eight (23 percent); Clostridium perfringens two
(6 percent); Escherichia coli O157:H7 three (9 percent); and Escherichia coli (enterotoxigenic)
one (3 percent).
The etiologic agent in 27 (36 percent) of the outbreaks was suspected or confirmed to be
caused by noroviruses. The IDPH laboratories were able to confirm seven (26 percent) of these
viral outbreaks. The remaining 20 (74 percent) outbreaks were classified as suspicious, largely
based on symptoms, incubation and duration of illness in the people who were affected.
One (1.3 percent) outbreak was confirmed to be caused by the chemical scombrotoxin
(histamine) in improperly handled fish.
One (1.3 percent) outbreak was confirmed to be caused by the parasite Cryptosporidium,
a single cell organism that produces gastrointestinal symptoms in human and animals. This
outbreak was investigated by the LHD with the assistance of the IDPH rapid response team. The
vehicle of transmission was determined to be recreational water.
Although thorough investigations were conducted, there was inconclusive evidence to
69
classify etiologic agents in 11 (15 percent) of the outbreaks and they were thus classified as
etiology unknown.
Foodhandlers were laboratory tested in 11 of the outbreaks (90 workers). In four of the
outbreaks, food handlers were found to be positive for the etiologic agent causing the illness, and
in three cases a food handler was implicated as the likely source.
Food was tested for pathogens in 24 (32 percent) of the outbreaks. Positive foods were
found in four (5 percent) of the samples tested. The responsible pathogens were E. coli O157:H7,
C. perfringens and histamine. By percentage, the largest single pathogen responsible for
foodborne illnesses is the norovirus, but unfortunately it is very difficult to culture these viruses
from foods. In food testing, viruses are most often implicated as the result of finding fecal
coliform bacteria in food samples, most likely accounted for by poor food handler hygiene.
The site of food preparation in these 75 outbreaks was restaurant, 44 (59 percent); home,
7 (9 percent); caterer, four, (5 percent), long-term care facility, three, (4 percent), grocery store,
three (4 percent), school, three (4 percent); and other, 11 (15 percent).
The sites where the food was consumed in 75 outbreaks was restaurant, 26 (35 percent);
home, 14 (19 percent); workplace, 10 (13 percent); school, five (7 percent); long-term care
facility, three (4 percent); and multiple or other, 17 (23 percent).
Factors that were identified as contributing to these 75 outbreaks were bare-handed
contact by food handler, 18 (24 percent), inadequate cleaning of processing/preparation
equipment/utensils, nine (12 percent); food handling by an infected person or carrier of a
pathogen, nine (12 percent); cross contamination from raw ingredient of animal origin, seven (9
percent); glove-handed contact by food handler, four (5 percent), raw product/ingredient
contaminated by pathogens from animal or environment, three (4 percent), and storage in
contaminated environment, three, (4 percent); and toxic substance part of tissue, one, (1 percent).
In 33 (44 percent) of the outbreaks, the investigation team could not identify any contributing
cause to the outbreak.
There were three outbreaks in 2001 that required the cooperative efforts of two local
health departments working together to complete the investigation. IDPH was the lead
investigating agency in a multi-county outbreak in which 19 positive cases of E. coli O157:H7
were identified. This outbreak also involved joint efforts by the USDA and FDA.
The proportion of reported cases caused by the major enteric pathogens can be found in
Figure 44. Table 6 provides a summary of all foodborne and waterborne outbreaks reported to
IDPH in 2001. These include sporadic and outbreak-related cases. In 2001, compared to
previous years, cryptosporidiosis cases made up a larger proportion of the reported enteric cases
because of a large recreational water outbreak in Tazewell County.
Summary
In 2001, Illinois recorded 74 foodborne and one waterborne outbreak compared to a fiveyear median of 52. The Department interprets the increase as a sign of improved reporting by
local health departments. The most common site of food preparation in the reported outbreaks
was restaurants. Food handlers who had bare-hand contact with food and the inadequate cleaning
of equipment and utensils were the most commonly reported contributing factors to outbreaks.
Both bacterial and viral agents were important causes of foodborne outbreaks. One large
waterborne outbreak of cryptosporidiosis was reported in 2001.
70
Suggested readings
Frye DM, Zweig Z et al. An outbreak of febrile gastroenteritis associated with
delicatessen meat contaminated with Listeria monocytogenes. Clin Inf Dis 2002;35:943-9.
Levy M, Johnson CG, Kraa E. Tonsillopharyngitis caused by food borne group A
streptococcus: A prison-based outbreak. Clin Inf Dis 2003;36:175-82.
MMWR. Outbreak of listeriosis associated with homemade Mexican-style cheese-North
Carolina, October 2002-January 2001.
MMWR. Food borne outbreak of Group A rotavirus gastroenteritis among college
students-District of Columbia, March-April 2000.
MMWR. Surveillance for waterborne-disease outbreaks-United States, 1999-2000.
MMWR 2002;51(SS-8). 1-47.
Potasman I, Paz A, Odeh M. Infectious outbreaks associated with bivalve shellfish
consumption: A worldwide perspective. CID 2002:35:921-28.
71
Table 5. Etiologic agent involved in 2001 outbreaks
Agent
Confirmed
B. cereus
0
0
B. cereus/S. aureus
0
8
B. cereus/C perfringens
0
12
C. perfringens
2
0
Cryptosporidium
1 (waterborne)
0
E. coli O157:H7
3
0
Enterotoxigenic E.coli
1
0
Norovirus
7
21
Salmonella
8
1
Shigella
0
0
Scombroid
1
0
S. aureus
0
0
Unknown (11)
72
Suspect
First
onset
date
1/1
1/2
1/12
1/13
1/19
1/28
2/12
2/18
2/25
3/12
3/13
3/18
4/1
4/5
4/14
IDPH
log #
2001-1
2001-4
2001-2
2001-3
2001-31
2001-6
2001-8
2001-9
2001-32
2001-11
2001-10
2001-12
2001-13
2001-14
2001-17
Canton
Hebron
Mattoon
Libertyville
Pekin
Chicago
Chicago
Hazel Crest
Woodstock
Maywood
Chicago
Robinson
Burbank
Chicago
Springfield
City of
exposure
Fulton
McHenry
Coles
Lake
Tazewell
Cook
Cook
Cook
McHenry
Cook
Cook
Crawford
Cook
Cook
Sangamon
County
4/4
4/5
10/13
4/4
10/10
40/85
14/unknown
3/3
6/10
2/2
2/2
10/19
20/30
22/unknown
23/120
# ill/#
exposed
D, HA, AC
D,AC,HA
D
V,D,F,AC,BA
V,D
V,D,F,AC,BA
V,D,F,AC
D, AC,F,HA
V,D,AC,HA
V,D, F,HA
AC, D, V
V,D
V
D,F,AC,BA
V,D
Symptoms1
72
4
8
14
7
73
unknown
39
15
30
5
.75
32
.5
25
unknown
Incub
(hrs)
Table 6. Food borne and waterborne outbreaks in Illinois, 2001
unknown
unknown
unknown
unknown
unknown
unknown
carrot sticks/
ranch
dressing
unknown
unknown
unknown
unknown
unknown
candy
unknown
unknown
Foods
implicated
Salmonella
brandenburg/
Salmonella enteritidis
S.aureus/B.cereus
C. perfringens/B.cereus
Salmonella enteritidis
S.aureus/B.cereus
Norovirus-G2,SR470
Norovirus
C. perfringens/B.cereus
Norovirus
S.aureus/B.cereus
unknown
Norovirus
unknown
Salmonella berta
Norovirus-G2, P2B
Agent
C
S
S
C
S
C
S
S
S
S
unknown
S
unknown
C
C
Status2
H,T
unknown
T
unknown
T
unknown
unknown
T
unknown
unknown
unknown
unknown
unknown
H,PF
unknown
Contributory
causes3
restaurant/workplace
restaurant/workplace
restaurant/restaurant
unknown/unknown
restaurant/home
restaurant/restaurant
bowling alley/
bowling alley
restaurant/home
home and restaurant/
home and restaurant
restaurant/home
restaurant/restaurant
restaurant/restaurant
store/school
restaurant/restaurant
LTC/LTC
Place of prep/
Place eaten4
First
onset
date
4/15
4/16
4/20
4/26
4/29
5/3
5/4
5/10
5/10
5/13
5/14
5/20
5/22
5/23
5/24
5/26
IDPH
log #
2001-16
2001-15
2001-33
2001-19
2001-18
2001-62
2001-30
2001-20
2001-21
2001-24
2001-23
2001-35
2001-27
2001-26
2001-28
2001-29
Carlyle
Orland Park
Matteson
Neponset
Charleston
E. Dubuque
Rockford
Chicago
Ridge
East Peoria
Belleville
Chicago
Arcola
Inverness
Chicago
Palatine
Bement
City of
exposure
Bond,
Clinton,
Madison
Cook
Cook
Bureau
Coles
Jo Daviess
Winnebago
Cook
Sangamon/
Tazewell
St. Clair
Cook
Douglas
Cook
Cook
Cook
Piatt
County
33/56
2/7
6/unknown
35/92
2/unknown
3/7
7/9
19/23
27/36
14/42
8/9
11/21
13/ unknown
3//3
2/2
11/17
# ill/#
exposed
D,AC
V,D,AC
V,D,AC
V,D,AC,HA
D,BA,AC
D,AC
V,AC,D,F, HA
D,AC
D,AC
V,D,F,AC
V,D,BA,F
V,D,AC
D
D,V,F,AC
V,D,AC
V,D,F,AC,HA,
BA
Symptoms1
12
5
15
74
unknown
60
25
27
12
12
28
36
24
unknown
36
7.5
34
Incub
(hrs)
mostaccioli
unknown
unknown
unknown
ground beef
unknown
unknown
beef
unknown
unknown
unknown
turkey
unknown
unknown
unknown
unknown
Foods
implicated
C.perfringens/ B.cereus
unknown
C. perfringens/B.cereus
Norovirus
E. coli O157:H7
unknown
Norovirus-G2 SR470
C. perfringens
C. perfringens/ B.
cereus
Salmonella Group C
Norovirus
Norovirus-G2 P2-B
unknown
Norovirus
unknown
Norovirus
Agent
S
unknown
S
S
C
unknown
C
C
S
S
S
C
unknown
S
unknown
S
Status2
T
unknown
unknown
unknown
U
unknown
H,PF
T
unknown
unknown
unknown
unknown
unknown
IF
unknown
H,FP
Contributory
causes3
caterer/banquet hall
restaurant/restaurant
restaurant/restaurant
school/school
home/home
home/home
restaurant/home
restaurant/workplace
home/school
restaurant/restaurant
restaurant/workplace
and home
restaurant/restaurant
long-term care
facility/
restaurant/restaurant
restaurant/restaurant
deli/home
Place of prep/
Place eaten4
First
onset
date
6/2
6/8
6/16
6/21
6/25
7/1
7/3
7/4
7/12
7/15
7/16
7/16
7/17
7/21
7/21
IDPH
log #
2001-37
2001-36
2001-34
2001-39
2001-38
2001-41
2001-71
2001-45
2001-48
2001-49
2001-50
2001-61
2001-51
2001-44
2001-47
Chicago
Lisle
Tremont
Arlington
Hgts
Champaign
multiple
Chicago
Crestwood
Chicago
Orland Park
Orland Park
Morton
Grove
Pekin
Orland Park
Chicago
City of
exposure
Cook
DuPage
Tazewell
Cook
Champaign
multiple
Cook
Cook
Cook
Cook
Cook
Cook
Tazewell
Cook
Cook
County
47/146
20/53
358/unknown
3/3
15/23
19/unk
4/4
6/6
3/3
2/2
3/9
10/15
27/56
8/14
6/unknown
# ill/#
exposed
D
D,AC
V,D,AC,F
V
V,D,AC,HA
D,BD,AC,F
D,V,BA,F,AC
N,V,AC,D,H
V,D,AC
AC,D,HA
AC,D
V,D,AC,HA,B
A
V,D
V,D,AC
D,F,AC,BA
Symptoms1
75
unknown
19
144
1.25
33.5
unk
unk
8.5-96
.75
5
7
39
36
38
44
Incub
(hrs)
unknown
water
recreation
water
unknown
unknown
ground beef
unknown
unknown
unknown
unknown
chicken
tetrazinni
unknown
chicken
quesadillas
and meatballs
unknown
unknown
Foods
implicated
Salmonella enteritidis
Norovirus
Cryptosporidium
S. aureus/B.cereus
Norovirus
E. coli O157:H7matching PFGE
Salmonella
typhimurium
C.perfringens /B.cereus
unknown
S.aureus/B.cereus
C. perfringens
Norovirus
Norovirus
Norovirus
Salmonella enteritidis
Agent
C
S
C
S
S
C
C
S
unknown
S
C
S
S
S
C
Status2
unknown
unknown
fecal accident
unknown
H
IC,U
unknown
unknown
unknown
unknown
T,S
unknown
H,IF
unknown
unknown
Contributory
causes3
long term care
facility
hotel/hotel
waterpark/waterpark
restaurant/workplace
home/home
home/home
restaurant/workplace
and restaurant
restaurant/restaurant
restaurant/restaurant
restaurant/restaurant
restaurant/restaurant
and home
conference/caterer
restaurant/restaurant
restaurant/restaurant
restaurant/restaurant
Place of prep/
Place eaten4
First
onset
date
8/5
8/5
8/11
8/11
8/18
8/18
8/19
8/25
8/28
9/1
9/19
9/21
9/21
9/25
10/3
10/3
IDPH
log #
2001-55
2001-72
2001-52
2001-57
2001-54
2001-56
2001-53
2001-58
2001-59
2001-60
2001-63
2001-77
2001-64
2001-65
2001-67
2001-68
Belleville
Kaneville
Palos Park
Effingham
Belleville
Hinsdale
Mattoon
Collinsville
Summit
Springfield
Crystal Lake
Oak Lawn
Chicago
Oak Park
Chicago
Schaumburg
City of
exposure
St. Clair
Kane
Cook
Effingham
St. Clair
DuPage
Coles
Madison
Cook
Sangamon
McHenry
Cook
Cook
Cook
Cook
Cook
County
51/ unknown
79/153
12/16
8/unknown
7/unknown
2/2
5/6
20/46
15/25
23/46
4/5
10/30
20/?
19/32
4/4
2/unknown
# ill/#
exposed
V,D,AC
V,D
V,AC,D
BD
V,D,AC
Flushing/
tingling
V,D,AC,HA,F,
BA
V,D,AC,H
V,D
D,AC
D,AC,F
D,AC
V,D,AC,F,BA
AC,D
V,D,AC,F
D,BA,AC,F,
HA
Symptoms1
76
unknown
unknown
35
unknown
9
.5
19
38
19
40
38
20
19
7
5
60
Incub
(hrs)
unknown
water
unknown
unknown
unknown
tuna
unknown
lemonade
unknown
unknown
unknown
sandwiches
carnitas
beef barbacoa
unknown
unknown
Foods
implicated
Norovirus-G1 P1-A
unknown
Norovirus
E.coli O157:H7
C. perfringens/ B.
cereus
scombrotoxin
Norovirus-G1 P1-A
Norovirus-G2 P1B,SR67D
C. perfringens/B.
cereus
ETEC-multiple strains
unknown
C. perfringens/ B.
cereus
Salmonella uganda
C.perfringens/ B.cereus
unknown
Salmonella enteritidis
Agent
S
unknown
S
C
S
C
C
C
S
C
unknown
S
C
S
unknown
C
Status2
unknown
unknown
H
unknown
T
T
H
H
T
sewage
contamination
H
unknown
C,T,FP
T
unknown
unknown
Contributory
causes3
school/school
school/school
restaurant/restaurant
unknown/unknown
fair/fair
restaurant/restaurant
restaurant/restaurant
home and
church/church
restaurant/home
restaurant/restaurant
restaurant/workplace
office
caterer/workplace
grocery store/home
restaurant/home
restaurant/restaurant
restaurant/restaurant
Place of prep/
Place eaten4
10/7
10/24
10/30
10/30
10/31
11/18
12/13
12/14
12/14
12/16
12/20
12/24
12/25
12/26
2001-69
2001-70
2001-73
2001-74
2001-86
2001-76
2001-81
2001-78
2001-79
2001-80
2001-82
2001-84
2001-83
2001-85
Chicago
Springfield
Springfield
Hillside
Burbank
Berwyn
Normal
Plano
Quincy
Elk Grove
Village
Chicago
Arlington Hts
Edwardsville
Tuscola
City of
exposure
Cook
Sangamon
Sangamon
Cook
Cook
Cook
McLean
Kendall
Adams
Cook
Cook
Cook
Madison
Douglas
County
5/unknown
14/22
8/12
2/2
27/41
5/6
15/31
18/18
14/18
5/unknown
5/6
5/11
5/7
63/107
# ill/#
exposed
V,D,AC
AC,D,V,BA
AC,D,V,F,
HA,BA
V,AC,D,HA
V,D,AC,F,BA
V,AC
V,D,AC,HA
V,F,AC
V,D
D,AC
AC,D
AC,D
V,AC
V,D,BA,AC
Symptoms1
3
24
37
34
29
10.5
37
36
32
16
6.5
13
1
31.5
Incub
(hrs)
unknown
unknown
unknown
unknown
dressing
hot dogs
pea&cheese
salad
unknown
unknown
unknown
unknown
unknown
unknown
fried chicken/
mashed
potato
Foods
implicated
S. aureus/B.cereus
Norovirus
Norovirus
Norovirus
Norovirus
unk
Norovirus-G2, not
further typed
Norovirus
Norovirus
C. perfringens/ B.
cereus
S. aureus/ B. cereus
C.perfringens/ B.cereus
S.aureus/ B.cereus
Norovirus
Agent
S
S
S
S
S
unknown
C
S
S
S
S
S
S
S
Status2
unknown
unknown
unknown
H
unknown
T,H,C
PF,IF,H
H
H
H
unknown
T,C
unknown
unknown
Contributory
causes3
restaurant/home and
work
home/home
home/home
restaurant/restaurant
restaurant/restaurant
restaurant/restaurant
retirement
home/retirement
home
restaurant/workplace
grocery/hotel
caterer/workplace
restaurant/workplace
restaurant/workplace
restaurant/restaurant
caterer/town center
Place of prep/
Place eaten4
2
77
BA=body ache, D=diarrhea, F=fever, H=headache, N=nausea, V=vomiting, C=cramps; > 40% ills reporting symptoms
S=suspect, C=confirmed
3
C=contaminated surfaces, H=inadequate food handler hygiene, IC=inadequate cooking, IF=ill food handler, PF=positive food handler, S-storage in contaminated area, T=improper holding temperatures,
U=unsafe food,
4
rest=restaurant
1
First
onset
date
IDPH
log #
Specific types of foodborne outbreaks
Bacillus cereus (B. cereus)
Bacillus cereus causes foodborne illness through intoxication. There are two types of
illness caused by B. cereus, depending on the enterotoxin elaborated by the organism. In one
type, the incubation period is from one to six hours and symptoms last 12 hours or less. Almost
all individuals experience vomiting and about one-third experience diarrhea. The illness is
caused by a preformed enterotoxin. Rice has been associated with this type of B. cereus in past
outbreaks. In the other type, the incubation period ranges from eight to 16 hours and symptoms
last less than 24 hours. Diarrhea is a prominent feature but vomiting is absent. Foods associated
with previous outbreaks include custards, cereals, and meat or vegetable dishes. The organism
multiplies rapidly at room temperature and the spores can survive boiling.
Case definition
Laboratory confirmation for B. cereus includes isolation of greater than 105 organisms
per gram in properly handled food or isolation of the organism from two or more ill people and
not from controls.
Descriptive epidemiology
•
Number of outbreaks reported in Illinois in 2001 - none confirmed. There were eight
outbreaks that may have been caused by either B. cereus or Staphylococcus aureus as
suggested by the clinical presentation and 12 outbreaks in which the clinical picture
suggested either B. cereus or C. perfringens.
Clostridium perfringens
Another foodborne intoxication is caused by C. perfringens enterotoxin. Diarrhea is
common but vomiting and fever are usually absent. The incubation period is eight to 16 hours
(usually 12 hours). The illness lasts one day or less. Almost all outbreaks are associated with the
inadequate heating or reheating of meats or gravies, which allows the organism to multiply. The
enterotoxin is heat-resistant.
Case definition
There are three ways to establish laboratory confirmation of a C. perfringens outbreak:
1) isolation of greater than 105 organisms per gram of food that has been properly handled for
testing, 2) demonstration of enterotoxin in the stool of two or more ills, or 3) isolation of greater
than 105 organisms per gram in the stool of two or more ill persons. The IDPH laboratory uses
the enterotoxin method for human stool specimens rather than quantification of organisms.
Descriptive epidemiology
•
Number of outbreaks reported in Illinois in 2001 - two confirmed; 12 were suspected to
be due to either C. perfringens or B. cereus but laboratory confirmation did not occur.
<
One outbreak of C. perfringens occurred after a catered work seminar in
Cook County in May 2001. Of the 23 people in attendance, 19 (83
percent) became ill and 100 percent of the ill persons had diarrhea. The
median incubation period was 12.5 hours. Roast beef was tested and
found to have an estimated 135 million C. perfringens per gram. Roast
78
<
beef was also implicated by epidemiology. Factors contributing to the
outbreak were slow cooling and improper food handling.
Another laboratory-confirmed outbreak took place in Cook County after
consumption of chicken tetrazinni sold at a restaurant in June 2001. The
median incubation period was seven hours. Three persons became ill and
all reported diarrhea and abdominal cramps. The chicken tetrazinni tested
positive, with 490,000 organisms per gram, but the food could not be
implicated epidemiologically due to small numbers of persons who were
exposed.
Enterohemorrhagic E. coli (E. coli O157:H7 and others)
Foodborne outbreaks of E. coli O157:H7 have been linked to undercooked ground beef,
apple cider, sprouts and lettuce. Other types of E. coli also can be pathogenic in humans and
cause outbreaks.
Case definition
Laboratory confirmation of an outbreak occurs when E. coli O157:H7 or other shiga-like
toxin-producing E. coli is isolated from stool of two or more ills or from the implicated food or
water.
Descriptive epidemiology
•
Number of outbreaks reported in Illinois in 2001 - three confirmed E. coli O157:H7.
<
An E. coli O157:H7 outbreak occurred in Coles County in June and was linked to
ground beef purchased at a grocery store. Stool samples from two persons tested
positive for E. coli O157:H7. Ground beef purchased by one of the sick persons
also tested positive. Isolates from the individuals and the beef matched by pulsed
field gel electrophoresis (PFGE). The two individuals reported diarrhea, bloody
stools, abdominal cramps and a median incubation period of five days.
<
Another outbreak occurred in multiple counties in July and August 2001.
Nineteen persons from six different northern Illinois counties tested positive for E.
coli O157:H7 with a matching PFGE pattern. All 19 reported diarrhea, 12 sought
medical care and eight were hospitalized. Seventeen (89 percent) reported
consumption of ground beef and 14 (74 percent) purchased ground beef from the
same grocery store chain. Meat samples from homes of three cases tested positive
and matched the outbreak strain. A case-control study was initiated but was
stopped due to media coverage of an unrelated USDA ground beef recall. The
media coverage of this ground beef recall might have influenced food history of
participants in the study.
<
A third E. coli O157:H7 outbreak occurred in September in Effingham County.
Eight students from the same high school became ill; seven were laboratory
confirmed cases. All cases reported diarrhea, seven reported bloody stools and one
reported vomiting. Half of the students were hospitalized and one developed
hemolytic uremic syndrome. No food or environmental source was implicated in
the environmental or epidemiological investigations.
79
Enterotoxigenic E. coli (ETEC)
Descriptive epidemiology
•
Number of outbreaks reported in Illinois in 2001 - 1 confirmed
<
The ETEC outbreak occurred in August with nine lab-confirmed cases and 12
probable cases linked to eating at a restaurant in Sangamon County. The food
vehicle could not be determined. The incubation period was 40 hours, and the
attack rate was 46 percent in the exposed group. There may have been sewage
backup into the ice machine area.
Salmonella
Salmonella is the most common causative agent associated with bacterial foodborne
outbreaks. The incubation period for Salmonella is six to 72 hours. Symptoms may include
diarrhea, vomiting, fever and headache.
Case definition
A laboratory-confirmed outbreak of Salmonella occurs when bacteria are either cultured
from implicated food or Salmonella of the same serotype is cultured from clinical specimens
from two or more ill individuals.
Descriptive epidemiology
•
Number of outbreaks reported in Illinois in 2001 – 123 people were ill from eight
confirmed and one suspected outbreak (mean = 14 persons ill per outbreak). The
outbreaks occurred in Cook (five in the city of Chicago), Fulton, Lake and St. Clair
Counties. The Salmonella enterica serotypes involved in the outbreaks were Enteritidis,
Berta, Typhimurium, Brandenburg and Uganda.
<
The first Salmonella outbreak of 2001 occurred in January in 22 persons from
different groups who ate at one restaurant in Chicago. The median incubation
period was 25 hours. Fifteen persons were laboratory confirmed with Salmonella
ser. Berta. Laboratory testing of food items did not establish a food vehicle. Food
handlers tested positive for the same serotype but also reported eating at the
restaurant.
<
In March, an outbreak of Salmonella ser. Enteritidis occurred in four individuals
in Lake County. The food suspected was leftover pigs feet but it could not be
implicated epidemiologically.
<
In Fulton County, four persons became ill after a meal in a restaurant. Two
persons tested positive for Salmonella but had different serotypes (ser. Berta and
ser. Brandenburg). One person was hospitalized. No food could be implicated
epidemiologically.
<
An outbreak sickening six persons from two different groups who ate at one
restaurant in Chicago was reported in June. Three of the persons tested positive
for Salmonella ser. Enteritidis. All reported diarrhea and fever, and two were
hospitalized. No food or environmental source was implicated in the
environmental or epidemiological investigations.
<
An outbreak of Salmonella ser. Enteritidis occurred in Chicago when 47 persons
(42 residents and five employees) of a nursing home became ill. Four individuals
were hospitalized. A wide distribution of cases over time suggests that exposure
80
<
<
<
<
was on-going, but no food or environmental condition could be implicated.
In July, a confirmed Salmonella ser. Typhimurium outbreak occurred in four
individuals who consumed food from the same restaurant in Chicago. Salmonella
was not isolated from any food or workers at the time of inspection.
In Cook County, two persons from separate households became ill after a meal at
the same restaurant. Both reported diarrhea, bloody stools, fever and abdominal
cramps; both were hospitalized. Salmonella ser. Enteritidis was found in stool
samples of both ill persons. No food vehicle could be determined.
The final Salmonella outbreak occurred in August in Chicago when 20 persons
became ill (12 confirmed with S. ser. Uganda). The median incubation period was
19 hours. Among those who were ill, 100 percent had diarrhea and 75 percent had
fever. Carnitas sold at one grocery store were implicated by epidemiology. One
food handler tested positive for Salmonella ser. Uganda.
A foodborne outbreak not previously reported came to IDPH’s attention in 2001.
The outbreak occurred in November 1995 in Monroe and Randolph counties
when 78 persons became ill after a meal of chicken and dumplings at a fundraiser.
Ill persons reported diarrhea, fever, abdominal cramps, body aches and headaches.
No food or environmental source was confirmed in the environmental or
epidemiological investigations.
Shigella
The Shigella organism is not a common cause of foodborne outbreaks. Instead, it causes a
gastrointestinal illness often transmitted from person to person. However, outbreaks have been
associated with bean dip, lettuce, parsley and contaminated water. Outbreaks of shigellosis have
also been associated with swimming in contaminated water. Forty-five persons became ill during
one shigellosis outbreak in Iowa in 2001 after use of a wading pool.
Case definition
The case definition for an outbreak of Shigella is identification of the same serotype of
the bacteria in two or more ill persons.
Descriptive epidemiology
•
Number of food or waterborne outbreaks reported in Illinois in 2001 - None confirmed
Suggested Readings
MMWR. Shigellosis outbreak associated with an unchlorinated fill-and-drain wading
pool-Iowa, 2001. MMWR 2001;50(37:797-800.
Staphylococcal food poisoning
One type of foodborne illness, classified as an intoxication, is caused by enterotoxinproducing strains of Staphylococcus aureus. Within 30 minutes to eight hours (usually two to
four hours) after eating contaminated food, a person may experience explosive vomiting and
diarrhea. The duration of illness is usually short – less than 24 hours. Humans are considered to
be the primary source of the organism in foodborne outbreaks. S. aureus can be found in nasal
passages, throat and hair and on the skin of healthy people; bacteria are present in high numbers
in cuts, pustules and abscesses. The enterotoxins produced by S. aureus are heat stable. The
81
organism may produce toxin in foods and then die so cultures of foods may be negative and yet
the foods contained the staphylococcal enterotoxin that made people ill. Foodborne outbreaks
caused by S. aureus and those caused by B. cereus preformed enterotoxin have similar incubation
periods and clinical syndromes.
Case definition
Laboratory confirmation of an outbreak attributable to S. aureus requires detection of
enterotoxin in food or organisms with the same phage type in stools or vomitus of two or more
cases or isolation of greater than 105 organisms per gram in properly handled food.
Descriptive epidemiology
•
Number of outbreaks reported in Illinois in 2001 - None confirmed. However, there were
eight outbreaks suspected of being either S. aureus or B. cereus.
Chemical agents
This category includes toxins – such as ciguatera and scombrotoxin – associated with fish
consumption. Ciguatera poisoning is caused by the ingestion of the toxin in predatory reef fish,
such as barracuda, amberjack and grouper. The toxin is initially produced by dinoflagellates that
are eaten by herbivorous fish, which are then consumed by the predatory fish. There is a test to
detect the toxin in fish. However, the toxic fish have a normal taste and appearance. The toxin
cannot be destroyed by cooking or freezing. Symptoms of diarrhea and vomiting develop within
three to six hours after consuming contaminated fish. Neurologic symptoms may follow and
persist for weeks or months. These neurologic symptoms include numbness, tingling of the
mouth and extremities, muscle pain and weakness, and reversal of temperature sensation. There
is no diagnostic test or treatment available for humans.
Scombrotoxin poisoning occurs when a person consumes fish with a high level of
histamine that can be produced in the muscle of fish after harvest. Some fish – such as tuna,
mackerel, bluefish, dolphin, bonito and saury – are more likely to have high levels of histamines
in their tissue. When there is temperature abuse of fish after harvesting, the potential for
outbreaks associated with scombrotoxin increases. The clinical signs of toxicity in people include
lip swelling, itching, a peppery taste in the mouth, nausea, vomiting, facial flushing, headache
and stomach pain. Symptoms usually only last a few hours and there are no lasting effects.
Case definition
The case definition for ciguatera toxin outbreaks is the demonstration of ciguatoxin in
epidemiologically implicated fish or a clinical syndrome among persons who have eaten a type of
fish previously associated with ciguatera fish poisoning.
The case definition for scombroid toxin outbreaks is demonstration of histamine in
epidemiologically implicated fish or a clinical syndrome among persons who have eaten a type of
fish previously associated with histamine fish poisoning.
Descriptive epidemiology
•
Number of outbreaks reported in Illinois in 2001 - One scombroid outbreak confirmed.
In April 2001, two persons experienced flushing, burning and headache after eating tuna
burgers at separate meals at a DuPage County restaurant. The incubation periods were 15
and 30 minutes. No fish was available for testing.
82
Parasitic agents
There are a variety of parasitic agents that can cause foodborne or waterborne outbreaks,
for example, Cryptosporidia, Cyclospora and Giardia. The incubation periods for parasitic
agents can be up to 25 days.
Descriptive epidemiology
•
Number of outbreaks reported in Illinois in 2001 – One confirmed. See waterborne
outbreak section.
Viral gastroenteritis
Noroviruses cause almost all of the outbreaks of acute non-bacterial gastroenteritis in the
United States. Estimates are that 23 million people are affected by noroviruses in the United
States each year. The most common cause of viral gastroenteritis are small round-structured
viruses (SRSV), commonly called norovirus. SRSV are caliciviruses and can be classified into
two genogroups: genogroup 1 (Norwalk virus, Southampton virus and desert shield virus) and
genogroup 2 (Toronota virus, Mexico virus, Hawaii virus, Bristol virus, Lordsdale virus,
camberwall virus, Snow Mountain agent and Melksham virus). G1 and G2 genogroups affect
humans and include five to 10 genetic clusters. Approximately three-quarters of outbreaks
identified as norovirus by CDC between 1997 and 2000 were due to G2 strains.
Noroviruses are transmitted through consumption of contaminated food or water, directly
from person to person and from airborne droplets produced during vomiting. The most common
method of spread is via the fecal-oral route. The virus is excreted in stool and vomitus for up to
10 days. The incubation period and duration of illness ranges from 24 to 48 hours. Virus
shedding peaks 25 to 72 hours after exposure to the virus. Within 48 to 72 hours after symptom
onset, virus concentration in the stool declines below levels detectable by electron microscopy.
However, a study in the Netherlands showed that viral shedding can occur for up to three weeks
after onset in approximately one-quarter of cases. Short-term immunity occurs after infection.
Vomiting, diarrhea, headache and body aches are commonly reported. A common feature of
Norovirus outbreaks is secondary transmission to household members not exposed to the
implicated food or water.
Humans are the only known reservoir for these viruses. These viruses cannot replicate
outside the human body and therefore will not multiply in food items. Characteristics of the virus
that facilitate spread include low infectious dose, high concentration of virus in stool, strain
diversity, environmental stability and prolonged shedding. Failure of an ill food handler to
perform proper handwashing may result in fecal contamination of food. Illness caused by SRSV
can be suspected based on incubation period, duration of illness, symptoms and the absence of
bacterial or parasitic pathogens in stool samples. Noroviruses can survive freezing and
temperatures of up to 60º C and can survive chlorine levels up to 10 ppm, which is in excess of
that normally present in public water systems.
The virus cannot be grown in cell culture; a polymerase chain reaction (PCR) test is used
to diagnose norovirus. Testing for viral gastroenteritis in humans is not useful for screening
individual samples but is useful when multiple samples are available in an outbreak.
Approximately 25 state health department laboratories, including those in Illinois, can do the RTPCR to detect norovirus. Norovirus can be present in stools for up to a week after illness onset.
Immunity is short-lived and appears to be strain specific. Since there are so many strains,
83
individuals can be repeatedly infected by Norwalk-like viruses during their lifetime.
Many outbreaks of norovirus have been reported. A group of Illinois residents attending
a youth camp in Virginia were associated with a large outbreak in July 2001. The attack rate in
the group was 10 percent. In other outbreaks, water was implicated as the source of the virus. An
outbreak of norovirus in Wyoming was due to water consumption from a sewage contaminated
well. An outbreak of norovirus in Italy in 2000 was also linked to water consumption. In this
outbreak, tap water contaminated with fecal bacteria affected more than 300 people.
Case definition
Several laboratory tests may help to confirm an outbreak related to norovirus. These
include positive results on RT-PCR, visualization of SRSV in electron microscopy of stool from
ill individuals, or a fourfold rise in antibody titer to norovirus seen in acute and convalescent sera
in most serum pairs. Multiple samples are needed from each outbreak to provide sufficient
specimens to verify the causative agent as norovirus. An outbreak is considered confirmed when
at least two ill persons have positive PCR results.
Descriptive epidemiology
•
Number of outbreaks reported in Illinois in 2001 – 21 suspected outbreaks of viral
gastroenteritis, based on clinical syndrome, incubation period and duration of illness.
Seven outbreaks, involving 121 people who experienced compatible illness, were
laboratory confirmed (median = 17 ill persons per outbreak); six were confirmed as the
G2 genogroup and one was confirmed as the G1 genogroup. The median incubation
period for the confirmed outbreaks was 29 hours. PCR confirmation was made from stool
from 21 persons. Seven people visited a health care provider and three were hospitalized.
The confirmed outbreaks occurred in Coles, Cook, Douglas, Madison, McLean,
Sangamon and Winnebago Counties.
<
In Coles County, five people became ill after a meal at a restaurant. The
incubation period was 19 hours. Two were confirmed for norovirus (G1). No
food could be implicated epidemiologically.
<
In March, a confirmed norovirus (G2) outbreak occurred in 40 individuals who
attended work meetings and lodged at a hotel in Chicago. Ill persons reported
nausea (100 percent), abdominal cramps (92 percent) and diarrhea (85 percent).
There appeared to be two peaks of illness, but no food vehicle could be
implicated.
<
An outbreak of norovirus (G2) occurred in Douglas County in April. Eleven
persons became ill (two confirmed norovirus genogroup 2) after eating a meal at a
wedding reception. Turkey was implicated by epidemiologic analysis.
<
An outbreak of genotype 2 norovirus was identified in persons who attended a
church dinner in Madison County in August. Among the 20 persons who were ill,
95 percent had diarrhea and 75 percent had vomiting. Three were laboratory
confirmed by RT-PCR. Lemonade was epidemiologically identified as the food
vehicle.
<
In McLean County, 15 people became ill in a retirement residence in December.
Laboratory investigation identified the genotype 2 norovirus in a food handler and
three residents. The median incubation period was 38 hours. An epidemiological
84
•
investigation implicated cheese/pea salad as the food vehicle.
<
In January, a confirmed norovirus (G2) outbreak affected 19 residents and four
employees of an intermediate care facility for persons with developmental
disabilities in Sangamon County. Of those ill, 78 percent reported diarrhea and 22
percent reported vomiting. No food item could be implicated in the outbreak.
<
An outbreak of norovirus occurred in Winnebago County in May involving seven
persons from three different households who became ill after sharing a meal from
a restaurant. Six tested positive for norovirus genogroup 2. The median
incubation period was 27 hours. No food vehicle was implicated
epidemiologically.
Food vehicle – In eight of the 27 outbreaks, the following food items were statistically
associated with illness: turkey; lemonade; cheese/pea salad; carrot sticks and ranch
dressing; chicken quesadillas and meatballs; water; fried chicken and mashed potatoes;
and dressing.
Suggested readings
Boccia D, Tozzi AE et al. Waterborne outbreak of Norwalk-like virus gastroenteritis at a
tourist resort, Italy. Emerg Inf Dis 2002;8(6):563-8.
Anderson AD, Heryford AG et al. A waterborne outbreak of Norwalk-like virus among
snowmobilers-Wyoming, 2001. JID 2003;187:303-6.
Rockx B, de Wit M, et al. Natural history of human calicivirus infection: A prospective
cohort study. CID 2002;35:246-52.
Frankhauser RL, Monroe SS et al. Epidemiologic and molecular trends of “Norwalk-like
Viruses” associated with outbreaks of gastroenteritis in the United States. JID 2002;186:1-7.
Bresee JS, Widdowson M-A. et al. Food borne viral gastroenteritis: Challenges and
opportunities. CID 2002:35:748-53.
MMWR. Norwalk-like virus-associated gastroenteritis in a large, high-density
encampment-Virginia, July 2001. MMWR 2002:51(30):661-3.
Waterborne outbreaks
One waterborne outbreak was reported in 2001 in Tazewell County. In August, the
Tazewell County Health Department was alerted to a number of individuals who had symptoms
of cryptosporidiosis. Epidemiologic analysis of a case-control study identified a municipal water
park as a source of exposure. Water samples from the park were positive for Cryptosporidium.
The Tazewell County Health Department staff, with the assistance of the IDPH rapid response
team and the CDC, identified 358 cases of disease. Of those cases, 77 were laboratory-confirmed
and 281 were probable cases without laboratory confirmation. The epidemic curve is shown in
Figure 45. The median age for both laboratory-confirmed and probable cases was 9 years. Of
the laboratory-confirmed cases, 95 percent reported diarrhea and 64 percent reported vomiting.
Of the probable cases, 100 percent experienced diarrhea and 46 percent reported vomiting.
Forty-eight (63 percent) cases saw a physician and seven (9 percent) were hospitalized. The
genotype of the organism was identified as type 1. Case patients were more likely to have
attended the water park and had pool water in their mouths and swallowed pool water than agematched controls. Reports of secondary transmission were limited, which may have been due to
public health efforts to educate the public on ways to prevent the spread of the disease. Fecal
85
accidents in the pool probably contributed to this outbreak. Control measures included hyperchlorination of the pools at the waterpark to maintain free chlorine levels of 20 ppm for eight
hours to inactivate Cryptosporidium. Following this hyper-chlorination, transmission ceased. As
a result of this investigation, the water park installed an ultraviolet system that inactivates
Cryptosporidium oocysts.
86
Giardiasis
Background
Giardia, which causes the disease giardiasis, is the most commonly diagnosed intestinal
parasite in public health laboratories. A common intestinal parasite of children, especially those
attending day care, it is spread from person to person through fecal-oral transmission and has a
median incubation period of seven to 10 days. Many infections are asymptomatic and repeated
infections can occur in the same person. There are three species of giardia: G. lamblia, G. agilis
and G. muris. The main human pathogen is G. lamblia. Cysts can remain viable for months, and
the infectious dose is low.
Persons at greatest risk are children in day care facilities, close contacts of these children,
men who have sex with men, backpackers, campers and persons drinking from shallow wells
contaminated by run-off containing the organism. The most commonly identified intestinal
parasite in international travelers is G. lamblia. Giardiasis peaks in late summer and early fall.
Metronidazole is the most frequent treatment in the United States.
Approximately 85 percent of infections can be diagnosed with a single stool specimen.
Diagnosis is made by identification of the parasite in wet mount staining with trichrome or iron
hematoxylin, by direct fluorescent antibody detection, or by enzyme immunosorbent assay.
Because of its long period of communicability, low infectious dose and environmental
resistance, giardiasis is easily transmitted. Preventive measures should include practicing good
hygiene, avoiding water or food that might be contaminated and avoiding fecal exposure during
sex with infected persons.
Case definition
The case definition for giardiasis in Illinois is the presence of diarrhea and the
identification of Giardia trophozoites or cysts in stool, or detection of antigen by the ELISA
antigen test. Carriers are those persons identified with Giardia trophozoites or cysts in the stool
but who have no symptoms of disease.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 904 (five-year median = 1,167); the
incidence rate was seven per 100,000 population. Reported cases have declined since
1996 (see Figure 46). In addition, there were 204 Giardia carriers (Giardia identified in
stool but no clinical disease) reported in 2001.
•
Age – Mean age of cases was 30. Three age groups showed high incidence: 1 to 4 years
of age, 30 to 39 years of age and 40 to 49 years of age (Figure 47).
•
Gender – 42 percent were female. Males appear to have a higher incidence in the 30 to 39
year age group.
•
Race/ethnicity – 89 percent were white, 8 percent were African American and 3 percent
were other races; 14 percent were Hispanic. There was a significantly higher proportion
of whites with giardiasis and a lower proportion of African Americans compared to the
Illinois population.
•
Seasonal variation – Most cases occurred in summer to fall, from June through October
(Figure 48).
•
Geographic variation – Highest incidence rates per 100,000 for giardiasis occurred in
87
central Illinois (Figure 49). One-year incidence rates for the period 1997 to 2001 ranged
from 0 to 30 per 100,000 population by county. Counties with the highest average annual
giardiasis incidence rates per 100,000 population from 1997-2001 were DeWitt (30),
Peoria (24), Champaign (21), Tazewell (19) and Jersey (18).
Summary
Giardiasis cases (904) decreased in 2001 compared to the previous five-year median
(1,167). Whites were overrepresented in the case population for giardiasis (89 percent) compared
to their representation in the Illinois population (73 percent); African Americans were
underrepresented among giardiasis cases (8 percent) compared to their representation in the
Illinois population (15 percent). The mean age was 30, and more cases occurred in the warmer
months of the year. Centrally located counties had the highest incidence of giardiasis in the state.
Suggested readings
Ryan ET, Wilson ME, Kain KC. Illness after international travel. NEJM 2002;
347(7):505-16.
88
89
Figure 49. Average Annual Giardiasis Incidence Rates per 100,000 by County, Illinois, 19972001
90
Hemolytic uremic syndrome (HUS)
Background
Hemolytic uremic syndrome (HUS) is characterized by acute renal failure,
thrombocytopenia and microangiopathic hemolytic anemia. Many microbes including Shigella
dysenteriae, Salmonella ser. Typhi, Campylobacter jejuni and E. coli O157:H7 have been linked
to HUS. HUS occurs primarily in children younger than 5 years of age after infection by a
diarrheal agent producing shiga toxin. HUS usually occurs within two to 14 days of onset of
diarrhea. Almost half of children with HUS require dialysis. The illness can involve the CNS,
pancreas, heart and other organs. Almost a quarter of patients in a study of HUS cases from 1987
through 1991 developed major neurologic complications, such as seizures. Death may occur in 6
percent to 10 percent of children with HUS. During 2001, 202 cases of HUS were reported to
CDC from 28 states. The median age was 5 years. Almost half of the cases occurred from June
to September.
Antibiotic therapy has been identified as a risk factor for HUS development and
antibiotics are typically withheld for treatment if patients have suspected E. coli O157:H7
infection.
Case definition
Laboratory criteria include both acute anemia with microangiopathic changes (i.e.,
schistocytes, burr cells or helmet cells) on peripheral blood smear and acute renal injury
evidenced by either hematuria, proteinuria or elevated creatinine level (i.e., greater than or equal
to 1.0 mg/dL in a child aged less than 13 years or greater than or equal to 1.5 mg/dL in a person
aged greater than or equal to 13 years, or greater than or equal to 50 percent increase over
baseline).
A probable case is an acute illness diagnosed as HUS or TTP that meets the laboratory
criteria in a patient who does not have a clear history of acute or bloody diarrhea in the preceding
three weeks, or an acute illness diagnosed as HUS or TTP that a) has onset within three weeks
after onset of an acute or bloody diarrhea and b) meets the laboratory criteria except that
microangiopathic changes are not confirmed.
A confirmed case is an acute illness diagnosed as HUS or TTP that both meets the
laboratory criteria and began within three weeks after onset of an episode of acute or bloody
diarrhea.
Descriptive epidemiology
•
Three cases of HUS for which no known pathogen was isolated from the person were
reported. These cases were reported to CDC as HUS. The three cases were in individuals
younger than 1 year of age, 19 years of age and 65 years of age. Onsets ranged from
January to August. Cases were residents of Peoria, Rockford and Will counties.
•
Ten cases of HUS were reported from persons with confirmed E. coli O157:H7. These
cases were reported to CDC as E. coli O157:H7, not as HUS. These 10 cases ranged in
age from 1 to 86 years of age. Onsets ranged from January to December, six from June 1
through September 30. At least five cases were put on dialysis; three were reported with
thrombotic thrombocytopenic purpura. Two cases were fatal. Three cases were linked to
outbreaks, one in Effingham County and one that occurred in northeastern Illinois and
91
was linked to ground beef consumption. Counties in which cases occurred were Coles
(1), DeKalb (1), Effingham (1), Lake (1), LaSalle (1), Tazewell (1), Will (3) and
Winnebago (3).
Summary
Overall, 13 cases of HUS were reported in Illinois in 2001, and 10 cases were confirmed
E. coli O157:H7 cases. Two cases of HUS were fatal; both were in confirmed E. coli O157:H7
cases.
Suggested readings
Banatvala N et al. The United States national prospective hemolytic uremic syndrome
study: Microbiologic, serologic, clinical, and epidemiologic findings. JID 2001;183:1063-70.
Grabowski EF. The hemolytic-uremic syndrome-toxin, thrombin and thrombosis. NEJM
2002;346(1):58-61.
MMWR. Summary of notifiable diseases-United States, 2001. MMWR
2003;50(53):p.xv.
Safdar N, Said A, Gangnon RE, Maki DG. Risk of hemolytic uremic syndrome after
antibiotic treatment of Escherichia coli O157:H7 enteritis. A meta-analysis. JAMA
2002;288(8):996-1001.
92
Hepatitis, viral
Viral hepatitis is the primary cause of hepatocellular carcinoma and is the eighth most
common cause of cancer in the world. Acute infections with hepatitis A, hepatitis B, hepatitis C,
hepatitis non-A, non-B non-C (NANBNC) and hepatitis B carriers are reportable in Illinois.
Cases of acute infection must have either jaundice or liver enzymes elevated above normal. On
April 1, 2001, reporting of acute hepatitis C became mandatory. Although testing is available for
hepatitis C, the role of currently available supplemental tests in diagnosing acute infection is
limited. Hepatitis A is usually transmitted by fecal-oral contact or, rarely, by contamination of
food by a food handler. Hepatitis B and C are transmitted through percutaneous and permucosal
exposure to infective body fluids that may occur through blood transfusions, sharing needles in
injection drug use, tattooing, acupuncture or needlestick injury. Hepatitis B can be transmitted
through sexual contact. Hepatitis C also may be transmitted through sharing of equipment for
intranasal cocaine use. For the purposes of this report, cases of hepatitis C and hepatitis non-A
non-B were combined into one category (hepatitis non-A non-B). In 2002, they will be reported
separately.
Of the 671 reported acute hepatitis cases in Illinois in 2001, 66 percent were hepatitis A,
32 percent were hepatitis B and 2 percent were hepatitis non-A, non-B (NANB). The percentage
of hepatitis A cases was lower in 2001 (66 percent) than in 2000 (79 percent) and the percentage
of hepatitis B cases was higher in 2001 (32 percent) than in 2000 (19 percent). A comparison of
characteristics of these types of hepatitis is found in Table 7 and includes only cases for whom
information was gathered on the hepatitis reporting form.
Jaundice was reported in 87 percent of hepatitis A cases, in 77 percent of hepatitis B
cases and in 44 percent of hepatitis NANB. Hospitalization occurred for 21 percent of hepatitis A
cases, 38 percent of hepatitis B cases and 11 percent of hepatitis NANB.
Risk factors for the four types of hepatitis are described in Table 8. Hepatitis NANB cases
were more likely to report a history of injection drug use (43 percent) than were hepatitis B (3
percent) or hepatitis A cases (0 percent). Hepatitis A cases were more likely to report travel
outside the United States or Canada (28 percent) compared to hepatitis B cases (7 percent) or
hepatitis NANB (0 percent). Cases reporting more than one sexual partner, from highest to
lowest, were hepatitis B (36 percent), hepatitis NANB (14 percent) and hepatitis A (13 percent).
Less than 6 percent of hepatitis cases of each type reported being employed in a medical field
that could entail blood contact. Cases who reported receiving tattoos, from highest to lowest,
were hepatitis B (6 percent), hepatitis A (2 percent) and hepatitis NANB (0 percent).
Suggested readings
Liang TJ, Ghany M. Hepatitis B e Antigen-The dangerous endgame of hepatitis B.
NEJM 2002;347(3):208-10.
93
Table 7. Demographic and clinical information for hepatitis A, B and NANB in Illinois, 2001
Hepatitis A
Factor
# (total #
reporting)1
Hepatitis B
%
# (total #
reporting) 1
Hepatitis NANB
%
# (total #
reporting)1
%
Demographics
Mean age
29 (440)
-
32 (218)
-
43
-
162 (441)
34.5
91 (217)
42.0
4(12)
33.3
Asian
28 (420)
6.7
6 (206)
2.9
1 (12)
8.3
African American
72 (420)
17.1
92 (206)
45.0
0 (12)
0
White
318 (420)
75.6
106(206)
51.4
10 (12)
83.3
Other
2 (420)
0.5
2 (206)
1.0
0 (12)
0
124 (424)
29.2
19 (190)
10.0
1 (11)
9.1
335 (385)
87.0
153 (200)
77.0
4 (9)
44.4
81 (376)
21.5
53 (141)
37.6
1 (9)
11.1
Female
Race
Hispanic
Clinical
Jaundice
Hospitalized
1
Deaths
0 (378)
0
0 (195)
0
0 (9)
number of cases reporting that factor (total number of cases interviewed about that factor)
Source: Illinois Department of Public Health, 2002
94
0
Table 8. Number and percentage of cases with risk factors for hepatitis A, B and NANB in
Illinois, 2001
Factor
Hepatitis A (N=441)
# (total #
reporting)1
Hepatitis B (N=218)
%2
# (total #
reporting)1
Hepatitis NANB
(N=12)
%2
# (total #
reporting)1
%2
Day care contact
10 (357)
2.8
2 (151)
0
0 (8)
0
Household contact of day care
26 (354)
7.3
6 (146)
4.1
0 (7)
0
Contact with a hepatitis A
69 (338)
20.4
4 (143)
2.8
0 (6)
0
Sexual contact
10 (67)
14.9
Household
31 (67)
46.2
Other
26 (67)
38.8
Food handler
13 (360)
3.6
1 (152)
0.6
0 (8)
0
Ate raw shellfish
21 (343)
6.1
8 (144)
5.5
0 (4)
0
8 (345)
2.3
0 (149)
0
0 (6)
0
99 (354)
28.0
11 (162)
6.8
0 (5)
0
2 (326)
0.6
15 (162)
9.2
0 (3)
0
11 (14)
78.6
Household
1 (14)
7.1
Other
2 (14)
14.3
Common source outbreak
Travel
Hepatitis B or C case contact
Sexual contact
Dialysis contact
0 (335)
0
3 (173)
1.7
0(8)
0
Medical field employee
7 (346)
2.0
10 (172)
5.8
0 (5)
0
1
number of cases reporting that factor (total number of cases interviewed about that factor)
Percentage is number of cases with the risk factor divided by total number with information provided on that risk
factor multiplied by 100.
2
Source: Illinois Department of Public Health, 2002
95
Table 9. Risk factor information for hepatitis A, B and NANB in Illinois, 2001 (continued)
Factor
Hepatitis A (N=441)
# (total #
reporting)1
Injection drug user
%2
Hepatitis B (N=218)
# (total #
reporting)1
Hepatitis NANB
(N=12)
%2
# (total #
reporting)1
%2
0 (326)
0
6 (170 )
3.5
3(7)
42.8
Heterosexual
161 (196)
82.0
133 (158)
84.1
6(6)
100
Homosexual
31 (196)
15.8
20 (158)
12.6
0 (6)
0
4 (196)
1.6
5 (158)
3.2
0 (6)
0
0
114 (254)
44.9
17 (143)
11.9
1 (7)
14.3
1
107 (254)
42.0
75 (143)
52.4
5 (7)
71.4
2-5
27 (254)
10.6
42 (143)
29.4
0 (7)
0
>5
6 (254)
2.4
9 (143)
6.3
1 (7)
14.3
Dental work
32 (308)
10.4
25 (167)
15.0
0 (6)
0
Other surgery
8 (313)
2.5
14(170)
8.2
1 (6)
16.7
Acupuncture
0 (308)
0
0 (165)
0
0 (5)
0
Tattoos
6 (324)
1.8
11(168)
6.5
0 (5)
0
Needlestick
3 (324)
0.9
2 (162)
1.2
0 (5)
0
111 (284)
39.1
9 (161)
5.6
0 (5)
0
Sexual preference
Bisexual
Number of sexual partners
Hepatitis B vaccine series
*Percentage is number of cases with the risk factor divided by total number with information provided on that risk
factor multiplied by 100.
Source: Illinois Department of Public Health, 2002
96
Hepatitis A
Background
Hepatitis A is one of the most frequently reported vaccine preventable diseases. The
hepatitis A rate in the United States in 2001 was four per 100,000. Hepatitis A is spread from
person to person by the fecal-oral route. HAV infection can spread in household members,
through day care centers, among persons who consume contaminated or uncooked food handled
by infected workers and among men who have sex with men (MSM). Young children who are
frequently asymptomatic when infected may play an important role in hepatitis A virus
transmission in communities. About 2 percent to 5 percent of hepatitis A cases reported in the
United States are linked to foodborne outbreaks. An outbreak of hepatitis A in Ohio in 1998 was
associated with consumption of green onions at a restaurant. The incubation period is 15 to 50
days. Onset of illness with hepatitis A can be abrupt with fever, anorexia, nausea and abdominal
discomfort, followed by jaundice. The disease can vary from one to two weeks of mild symptoms
to a severe illness lasting months. Severity generally increases with age and many infections are
asymptomatic, especially in young children. Peak levels of the virus appear in the feces one to
two weeks before symptom onset and diminish rapidly after symptoms appear. Serologic testing
for IgM anti-HAV is required for laboratory confirmation of hepatitis A infection. IgM anti-HAV
becomes detectable five to 10 days after exposure and can persist for up to six months.
HAV can be prevented by good personal hygiene, particularly handwashing, preexposure
or postexposure immunization with immune globulin (IG), and preexposure immunization with
hepatitis A vaccine. The administration of IG for persons exposed to hepatitis A is 85 percent
effective in preventing symptomatic hepatitis A infection if given within two weeks of exposure
and may prevent infection entirely if given soon after exposure. The effect of IG starts within
hours of administration and provides from three to six months of protection.
Hepatitis A vaccines have been available in the United States since 1995. In a California
study of the effectiveness of the vaccine in a community experiencing an outbreak of hepatitis A,
36 percent of case patients reported contact with hepatitis A cases and 10 percent reported illegal
drug use. Vaccination decreased the incidence rate from 48 per 100,000 prior to vaccination to
21 per 100,000 after a community vaccination program. Hepatitis A vaccination induces
protection as soon as 17 to 19 days after vaccination for more than 50 percent of recipients. CDC
has recommended hepatitis A vaccination for men who have sex with men, certain travelers,
injection drug users, certain occupations, persons with chronic liver disease and children in
communities with high rates of hepatitis A. In at study of MSMs in 10 U.S. cities in 2000, it was
estimated that 35 percent were vaccinated for HAV.
Case definition
The CDC case definition for a case of hepatitis A is used in Illinois: an illness with a
discrete onset of symptoms and jaundice or elevated serum aminotransferase levels, and IgM
anti-HAV positive serology.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 441 (five-year median = 821) (Figure 50).
•
Age – Incidence was highest in 5- to 9-year-olds (7.6 per 100,000) (mean age = 25)
(Figure 51). The overall incidence rate for hepatitis A was 3.5.
97
•
•
•
•
•
•
•
Gender – Among those ages 20-49, the incidence of hepatitis A in males was higher than
in females.
Race/ethnicity – 76 percent were white, 17 percent African American and 7 percent other
races; 29 percent were Hispanic. Hispanics were overrepresented in the case population
(29 percent) compared to the Illinois population (12 percent).
Employment - 4 percent of hepatitis A cases were foodhandlers.
Seasonal variation – Cases increased in August and September (see Figure 52).
Geographic variation – The counties with the highest average annual incidences of
hepatitis A per 100,000 population for 1997 to 2001 were Boone (10), Madison (10),
Cook (9), Winnebago (9), Bureau (7) and Kane (6). The average annual incidence of
hepatitis A by county, from 1997 to 2001, can be found in Figure 53.
Risk factors – Contact with a hepatitis A case (20 percent), travel outside the United
States or Canada (28 percent) and consumption of raw shellfish (6 percent).
Symptoms/outcomes – 87 percent of reported cases were jaundiced. Almost one-quarter
of cases were hospitalized. Four deaths were linked to acute hepatitis A.
Summary
Hepatitis A is the most commonly reported acute infectious hepatitis in Illinois. The
incidence rate (3.5 per 100,000) was similar to the national incidence (4.0 per 100,000). The
mean age of cases was 29 years, although the highest incidence in 2001 occurred in 5- to 9-yearolds. Hispanics were overrepresented in hepatitis A cases.
Suggested readings
Averhoff F, Shapiro CN et al. Control of hepatitis A through routine vaccination of
children. JAMA 2001;286(23):2968-73.
Kahn J. Preventing hepatitis A and hepatitis B virus infections among men who have sex
with men. Clin Inf Dis 2002:35:1382-87.
Maddrey WC. Update in Hepatology. Hepatitis A. Ann Intern Med 2001;134:216-217.
MMWR. Summary of notifiable diseases-United States, 2001. MMWR
2003;50(53):p.xv.
98
99
Figure 53. One-year hepatitis A incidence rates per 100,000 by county, Illinois,
1997-2001
100
Hepatitis B
Background
Hepatitis B virus is a DNA virus that can be transmitted sexually, parenterally and
perinatally. Examples of transmission modes include injection drug use, hemodialysis,
acupuncture, tattooing, blood transfusions and needle-stick injuries among health care personnel.
Sexual and perinatal transmission occur from mucous membrane exposures to infectious blood
and body fluids. Men who have sex with men are at increased risk for hepatitis B. Approximately
35 percent of cases of acute hepatitis B occur in people who report no recognized risk factor. The
most commonly reported risk factors for transmission in the United States are high-risk sexual
activity and injection drug use. The incubation period is 45 to 180 days (average 60 to 90 days).
Positivity for HBeAg is linked to an increased risk of hepatocellular carcinoma.
Fewer than half of acute hepatitis B cases will have jaundice (<10 percent of children and
30 percent to 50 percent of adults). The onset is usually insidious with anorexia, nausea,
vomiting, abdominal discomfort, jaundice, occasional arthralgias and rash. Chronic HBV
infection is found in about 0.5 percent of adults in North America. An estimated 15 percent to 25
percent of persons with chronic hepatitis B will progress to cirrhosis or hepatocellular carcinoma.
A vaccine became available in 1982. In Illinois, hepatitis B vaccination in children was
mandated in 1997. CDC recommends vaccination for MSMs, certain travelers, injection drug
users, heterosexuals with multiple sex partners or with sexually transmitted diseases, clients or
staff in institutions for the developmentally disabled, health care workers with blood contact,
some immigrants, hemodialysis patients, household contacts and sexual partners of hepatitis B
virus carriers, and male prison inmates. In a study of MSMs in 10 cities in the United States in
2000, 39 percent reported receiving three doses of hepatitis B vaccine.
In a CDC study of enhanced sentinel surveillance sites in the United States, acute
hepatitis B declined from 14 cases per 100,000 in 1987 to three cases per 100,000 in 1998. The
study also indicated that more than half of acute hepatitis B cases in these sites might have been
prevented through routine hepatitis B immunization in STD clinics and correctional health care
programs.
During 2001, 7,843 acute hepatitis B cases were reported to CDC.
Case definition
The CDC case definition is used as the surveillance case definition for hepatitis B in
Illinois: a clinical illness with a discrete onset of symptoms and jaundice or elevated serum
aminotransferase levels, and laboratory confirmation. Laboratory confirmation consists of IgM
anti-HBc-positive (if done), or HbsAg-positive, and IgM anti-HAV-negative (if done).
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 218 confirmed acute cases (five-year
median = 230) (Figure 54). The overall one-year incidence rate of reported acute hepatitis
B in Illinois was 1.8 case per 100,000 population.
•
Age –The 20 -to 29-year-old age group experienced the highest incidence rate (4 per
100,000 population). The mean age was 38 years. (Figure 55).
•
Gender – 58 percent were male. There was a significantly higher proportion of males
among hepatitis B cases than among the Illinois population.
•
Race/ethnicity – 45 percent of cases were African American, 51 percent were white and 3
101
•
•
percent were Asian; 10 percent were Hispanic.
Risk factors - Those occurring in cases from six weeks to six months prior to illness
included more than one sexual partner (34 percent), MSM (13 percent), sexual contact
with a hepatitis B case (7 percent), employment in a medical field that entails blood
contact (6 percent), tattoos (5 percent), injection drug use (3 percent) and needlestick
injury (1 percent).
Symptoms/outcomes - 77 percent of hepatitis B cases were jaundiced and almost 38
percent were hospitalized.
Summary
There were 218 confirmed hepatitis B cases reported in Illinois in 2001. Although the
number of reported cases declined during the period 1996 to 2000, the number in 2001 rose to
near the 1998 level. Almost three-quarters of the cases were jaundiced and one-third were
hospitalized.
Suggested readings
Goldstein ST, Alter MJ et al. Incidence and risk factors for acute hepatitis B in the
United States, 1982-1998: Implications for vaccination programs. JID 2002;185(6):713-9.
Kahn J. Preventing hepatitis A and hepatitis B virus infections among men who have sex
with men. CID 2002;35:1382-7.
Maddrey WC. Update in Hepatology. Hepatitis B. Ann Intern Med 2001;134:217-219.
MMWR. Summary of notifiable diseases-United States, 2001. MMWR 2003;
50(53):p.xv.
Yang H-I et al. Hepatitis B e antigen and the risk of hepatocellular carcinoma. NEJM
2002;347(3):168-174.
102
103
Hepatitis non-A non-B
Background
For the purposes of this report, hepatitis C will be included in the hepatitis non-A non-B
(NANB) category. Hepatitis C virus (HCV), an RNA virus, is the most common chronic
bloodborne infection in the United States. There are at least six distinct genotypes of HCV; types
1a and 1b are most common in the United States. It is estimated that 1.8 percent of United States
residents have been infected with HCV. The incubation period for HCV ranges from two weeks
to six months, most commonly six to nine weeks. Many individuals are asymptomatic and only a
small proportion become jaundiced. Forty percent of infected adults are symptomatic, and 85
percent of adults with acute hepatitis C develop persistent infection. Acute hepatitis C is
uncommon.
The most efficient route of transmission is by direct percutaneous exposure (e.g., blood or
blood product transfusion, organ or tissue transplants, or sharing of contaminated needles
between injection drug users [IDUs]). Low efficiencies of transmission occur from sexual and
household exposure to an infected contact. Transmission of HCV has been reported from patient
to health care worker. The majority of HCV cases are in IDUs. The virus has been shown to be
transmitted by the use of shared drug preparation equipment such as drug cookers and filtration
cotton. A study among Chicago IDUs revealed that sharing of injection equipment other than
syringes may be important in HCV transmission. In the United States, injection drug use
accounts for 60 percent of HCV infection, sexual contact account for 20 percent and other
exposures (household, perinatal and occupational) for 10 percent. Ten percent of cases have no
identified risk factor. The rate of transmission after needle-stick injury from a known infected
person is less than 10 percent.
The hepatitis C virus can cause chronic hepatitis, cirrhosis and hepatocellular carcinoma.
Among adults who had acute hepatitis C, 26 percent to 50 percent developed chronic active
hepatitis and 3 percent to 26 percent developed cirrhosis. In a study of transfusion related
hepatitis C in the United States from 1968 through 1980, the risk for developing cirrhosis was 17
percent. Heavy alcohol use increased the risk for developing cirrhosis. Anti-HCV positive
persons had a 5- to 50-fold higher risk of primary hepatocellular carcinoma compared to antiHCV negative patients. These sequelae typically take 20 or more years to develop. Hepatitis C
related disease is the leading indication for liver transplantation. Approximately 40 percent of the
liver transplantations done in the United States are done because of hepatitis C related liver
disease.
Routine screening for HCV infection is recommended only for persons who have a
history of injecting drugs, recipients of clotting factor concentrates prior to 1987, recipients of
blood transfusions or solid-organ transplants prior to July 1992, and chronic hemodialysis
patients. Screening is also recommended for sex partners of HCV-infected persons, infants 12
months or older who were born to HCV-infected women, and health care workers after
accidental needle-sticks or mucosal exposure to anti-HCV-positive blood. There is no vaccine or
effective post-exposure prophylaxis to prevent HCV infection.
Diagnostic tests for HCV infection include serologic assays for antibodies and molecular
tests for viral particles. Screening tests for HCV include enzyme immunoassays (EIAs) to
measure anti-HCV antibody. While these tests are highly sensitive, they do not distinguish
between acute, chronic or resolved infections. False-positive results are common, resulting in the
need for supplementary testing. Diagnostic testing for HCV should include use of both an
104
enzyme immunoassay (EIA) and supplemental or confirmatory testing with a more specific assay
such as the recombinant immunoblot (RIBA, Chiron Corporation). RIBA results are reported as
positive, indeterminate or negative. It is not as sensitive as the EIA and should not be used for
screening. Guidelines on laboratory testing for HCV were distributed in a 2003 MMWR (See
suggested readings).
Qualitative tests for HCV can be used to assess the response to antiviral therapy. The
reverse transcription-polymerase chain reaction (RT-PCR) can detect HCV RNA in serum within
one to two weeks after exposure to the virus. This test can be used for early diagnosis, in
immunocompromised patients (whose antibody production may be impaired) and in patients with
indeterminate RIBA results. The RIBA antibody tests do not distinguish between acute, chronic
or resolved infection.
Persons with chronic hepatitis C should not drink alcohol and should be vaccinated for
hepatitis A and hepatitis B. HCV-positive persons should not donate blood, organs, tissues or
semen. There is insufficient data to recommend that infected persons change sexual practices
with steady partners. HCV-positive household members should not share toothbrushes or razors.
Treatment for hepatitis C may be recommended for persons with elevated serum alanine
aminotransferase (ALT) and tests that indicate the presence of circulating HCV RNA. HCV RNA
levels do not correlate with grade or stage of disease. HCV is divided into six genotypes.
Genotype is a predictor of response to therapy. Genotype 1a and 1b HCV infection, the most
common types in the U.S., has a poorer response to therapy than other types. Response to therapy
is higher in those with genotypes 2 and 3.
Reporting of acute hepatitis C infection (a person with a supplementary positive test for
hepatitis C) began in Illinois on April 1, 2001.
Case definition
The CDC case definition is used in Illinois for hepatitis NANB (this encompasses what
CDC defines as reportable hepatitis C, but does not require specific hepatitis C serology). It
requires a discrete onset of symptoms and jaundice or elevated serum aminotransferase levels (>2
½ times the upper limit of normal). Laboratory confirmation requires IgM anti-HAV-negative,
IgM anti-HBc negative (if done) or HBsAg negative.
Descriptive epidemiology
•
Number of cases in Illinois in 2001 – 12 cases of acute hepatitis NANB. Four were
classified as hepatitis C. Three cases who had an ELISA test for hepatitis C tested
positive; the test type on the other hepatitis C case is unknown.
•
Age – Hepatitis NANB cases ranged from 23 to 76 years (mean age = 42) (see Figure 56).
•
Gender – 75 percent of hepatitis NANB cases were male.
•
Race/ethnicity – For hepatitis NANB cases, 87 percent of cases were white and 12
percent were Asian; 12 percent were Hispanic.
•
Risk factors – For hepatitis NANB, three of seven (43 percent) cases reported a history of
injection drug use.
•
Symptoms/outcomes – 11 percent of hepatitis NANB cases were hospitalized and no
cases were fatal.
Summary
In 2001, there were 12 cases of reported hepatitis NANB including four cases of hepatitis
105
C. Among those for whom the information was available, 43 percent had a history of injection
drug use.
Suggested readings
Alter MJ, Kuhnert WL and Finelli L. Guidelines for laboratory testing and result
reporting of antibody to hepatitis C virus. MMWR 2003; 52(RR-3):1-16.
Harris DR et al. The relationship of acute transfusion-associated hepatitis to the
development of cirrhosis in the presence of alcohol abuse. Ann Intern Med 2001;134:120-4.
Lauer GM, Walker BD. Hepatitis C virus infection. NEJM 2001;345(1):41-52.
Maddrey WC. Update in Hepatology. Hepatitis C. Ann Intern Med 2001;134:219-221.
Rosenberg PM. Hepatitis C: a hepatologist’s approach to an infectious disease. CID
2001;33:1728-32.
Thorpe LE et al. Risk of hepatitis C virus infection among young adult injection drug
users who share injection equipment. AJE 2002;155:645-53.
Weber DJ, Rutala WA. The emerging nosocomial pathogens Cryptosporidium,
Escherichia coli O157:H7, Helicobacter pylori, and hepatitis C: Epidemiology, environmental
survival, efficacy of disinfection, and control measures. Inf Control Hosp Epid 2001; 22: 306315.
106
Histoplasmosis
Background
Histoplasmosis is a systemic fungal disease caused by Histoplasma capsulatum.
Transmission occurs through inhalation of the organism. The incubation period ranges from three
to 17 days. Signs and symptoms of histoplasmosis include fever, headache, muscle aches, cough
and chest pain. Patients who have underlying lung disease may develop chronic lung disease after
H. capsulatum infection. Bird and bat droppings are beneficial to the growth of the organism.
Diagnosis of infection can be through culture or serology. The M precipitin alone indicates active
or past infection. The H precipitin indicates active disease or recent infection.
Histoplasmosis can be a severe infection in persons with HIV or other
immunocompromising conditions. Approximately 5 percent of persons with AIDS who live in
endemic areas may develop histoplasmosis, which frequently disseminates.
Case definition
The case definition for histoplasmosis in Illinois is either –
1)
Isolation of the organism from a clinical specimen in patients with acute onset of flu-like
symptoms, or
2)
In patients with flu-like symptoms, hilar adenopathy and/or patchy infiltrates found on
chest radiograph, if done, and at least one of the follwing
a)
M or H precipitin bands positive by immunodiffusion
b)
A four-fold rise between acute and convalescent complement fixation (CF) titers
c)
A single CF titer of >1:32
d)
Demonstration of histoplasma polysaccharide antigen by radioimmunoassay
(RIA) in blood or urine, or demonstration of organisms by silver staining blood
specimens or biopsy material
3)
Probable case: clinically compatible illness and epidemiologic link to known outbreak
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 98 (five-year median = 43) (Figure 57). At
least 23 (23 percent) of these cases were in immunocompromised persons; therefore, it is
not possible to determine whether they represent new infections or reactivation of
previous infections.
•
Age – Mean age was 36 (Figure 58).
•
Race/ethnicity – 91 percent were white and 9 percent were African Americans; 4 percent
were Hispanic.
•
Disease type – 51 cases had information available; cases localized to respiratory system
(44 cases) and disseminated (seven cases). Of 54 cases with chest X-ray results, 80
percent had abnormalities.
•
Symptoms – Symptoms included fever (83 percent), shortness of breath (68 percent) and
cough (68 percent).
•
Diagnosis – 14 cases were probable (linked to two known outbreaks), 32 cases were
confirmed by culture. Twenty were M band positive by immunodiffusion; 20 had CF
titers and four had demonstration of organism in tissue. For eight cases the diagnostic
method was not available at the time this report was written.
•
Seasonal variation – No seasonal trend (Figure 59).
107
•
•
•
•
Geographic variation – The three counties reporting the most cases were Champaign (20),
Macon (17) and Cook (12).
Reports of exposure to the following – The following exposures were reproted by cases:
construction (61 percent), excavation (29 percent), dirt arenas (14 percent), potting soil
(10 percent), plowing (9 percent), attics (9 percent), caves (2 percent) and pigeon
droppings (2 percent).
Outcomes – 47 percent were hospitalized; four cases were fatal.
Outbreaks – 29 (29 percent) of cases were associated with two outbreaks in Illinois.
Outbreaks of histoplasmosis
Two outbreaks of histoplasmosis occurred in Illinois residents in 2001. One occurred in
groups of students traveling outside of the United States and the other outbreak occurred in outof-state residents working at a worksite in central Illinois.
IDPH was notified by CDC of a suspected outbreak of histoplasmosis in students from
multiple states, including Illinois, who participated in a spring break trip in Mexico. Thirty-one
university students from two central Illinois universities visited Mexico from March 10 to March
17. Of the Illinois students, 10 were laboratory confirmed (M band on immunodiffusion or $
1:32 titer on immunofluorescence testing). Twelve were not laboratory confirmed but met a
clinical case definition of fever and at least one of the following: headache, chest pain or
shortness of breath. These 12 were recorded as probable cases. Illness onsets ranged from March
15 to April 19. All had localized disease and all survived.
Signs and symptoms reported by the 22 cases included fever (21, 95 percent), chest pain
(16, 73 percent), shortness of breath (13, 59 percent), cough (17, 77 percent) and headache (15,
75 percent). One individual could not remember a fever, but was considered a probable case
because of chest pain and cough. Two cases were hospitalized.
Nineteen individuals (86 percent) had chest X-rays taken. Results were available for 13;
eight had abnormal chest X-rays consistent with histoplasmosis. Eighteen individuals (82
percent) submitted acute sera and eight (44 percent) were positive. Four (18 percent) submitted
convalescent sera and four were positive. Students from other states also developed
histoplasmosis. No known site of bird or bat droppings was present near the hotel in Mexico.
The second outbreak of histoplasmosis occurred in eight out-of-state workers from one
company at a landfill in central Illinois. The clustering of illness onsets in early May indicated a
point source for transmission. The work activity most likely to have resulted in transmission of
histoplasmosis, which occurred during the week most likely to have been the exposure time
(April 21 to April 28), was uprooting of large trees and moving of top soil in one area of the
landfill. This work was thought to have occurred from April 23 to April 25. Other work
performed by these employees did not involve the moving of topsoil, but rather dirt that was very
deep. Therefore, the most likely material of concern was the area surrounding and below the
felled trees. These employees were from out-of-state and may have been more susceptible to
histoplasmosis than workers who had lived in the area for years. Other clusters of histoplasmosis
have been associated with moving dirt, the felling of trees or the chipping of dead trees. After
removal and burial of the downed trees and topsoil suspected of being the source of the cluster
using appropriate precautions, no further histoplasmosis cases were reported from workers at the
site. Temporary workers in Illinois are counted as Illinois cases using CDC guidelines.
108
Summary
Almost 100 cases of histoplasmosis were reported in Illinois residents in 2001. This is a
large increase over the five-year median. The number as well as the temporal and geographic
variation of the cases were due to two outbreaks of histoplasmosis.
109
110
Legionellosis
Background
Legionellosis is caused primarily by Legionella pneumophila. However, 19 other
Legionella species have been documented as human pathogens based on isolation from clinical
material. The two major clinical manifestations of infection with Legionella bacteria are
Legionnaires’ disease (legionellosis) and Pontiac fever. Legionnaires’ disease may be epidemic
or sporadic, nosocomial or community acquired. The incubation period for Legionnaires’ disease
is two to 10 days (average five to six days) and, for Pontiac fever, it is five to 66 hours (average
24-48 hours). Initial symptoms of both are anorexia, myalgia and headache often followed by a
nonproductive cough and diarrhea. Patients with legionellosis clinically have pneumonia and
abnormal chest radiographs. Legionella species are found in natural and man-made water
environments.
Legionellosis most often occurs in those who are immunocompromised due to disease or
aging. Risk factors are underlying medical conditions such as human immunodeficiency virus,
organ transplantation, renal dialysis, diabetes, chronic obstructive pulmonary disease, cancer,
immunosuppressive medication or smoking. Pontiac fever is an acute, febrile illness with a high
attack rate, short incubation period and rapid recovery. Most cases are sporadic (not associated
with a known outbreak). Outbreaks have been associated with aerosol producing devices such as
whirlpool spas, showers, humidifiers, respiratory care equipment, evaporative condensers, air
conditioners, grocery store mist machines and cooling towers, and have occurred in industrial
settings.
Legionella urine antigen testing and culture of respiratory secretions are useful for
diagnostic testing. The urine antigen test provides rapid diagnosis for L. pneumophila serogroup
1 but will not provide an isolate to compare to clinical and environmental isolates gathered
during outbreak investigations. Urine antigen tests can produce a result within 15 minutes.
Legionella in the urine can be identified as early as one day after symptom onset and may persist
for days to weeks. Culture requires adequate processing of specimens and special media. Growth
may take three to five days. Lower respiratory tract specimens are the specimens of choice for
culture. However, fewer than half of patients with Legionnaires’ disease produce sputum. Culture
of Legionella in any human specimen indicates disease as Legionella is not a colonizing
organism. Testing for Legionella species is not performed by the IDPH laboratory. Most test
results among reported cases are from hospital or commercial laboratories.
From 1980 to 1998, diagnostic testing for Legionella cases in the United States switched
from serology to urine antigen testing. Urine antigen testing increased from 0 percent to 69
percent of reported cases from 1980 to 1998 in the U.S.
In 2001, the overall U.S. reported rate of legionellosis was 0.42 cases per 100,000
population. However, population-based studies indicate the rate may be more than 10 times this
number. Estimates are that only 2 percent to 5 percent of Legionnaires’ disease cases are reported
to public health officials.
Case definition
A confirmed case in Illinois is one that meets the CDC case definition, i.e., a clinically
compatible illness with laboratory confirmation of disease by 1) isolation of Legionella from
lung tissue, respiratory secretions, pleural fluid, blood or other normally sterile sites; or 2)
demonstration of a fourfold or greater rise in the reciprocal indirect fluorescence (IF) antibody
111
titer to $ 128 against L. pneumophila serogroup 1 between paired acute and convalescent phase
serum specimens; or 3) demonstration of L. pneumophila serogroup 1 in lung tissue, respiratory
secretions, or pleural fluid by direct fluorescent antibody (FA); or 4) demonstration of L.
pneumophila serogroup 1 antigens in urine by radioimmunoassay (RIA) or enzyme-linked
immunoassay (ELISA).
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001– 24 (five-year median = 35). Case report
forms were available for all 24 of the cases.
•
Age – 79 percent were greater than 50 years of age (Figure 60).
•
Geographic distribution – 10 cases were reported from Cook County.
•
Risk factors – Five of 22 (23 percent) stayed or worked in a hospital in the two weeks
before onset; seven of 18 with information available (39 percent) visited a hospital as an
outpatient. One case (5 percent) had been hospitalized continuously for three or more
days before onset; three (16 percent) were discharged from the hospital within 10 days
before onset; 12 (63 percent) had no hospital visits in the 10 days before symptoms; and
five cases had no information on hospital visits. Six of 15 (40 percent) traveled overnight
in the two weeks prior to onset. At least one underlying health problem (diabetes, cancer,
transplant, renal dialysis, corticosteroid therapy, other immunosuppressive condition or
smoking) was reported by 18 of 24 (75 percent) cases; four reported no underlying health
problems and information was incomplete for two cases.
•
Diagnosis – Cases were diagnosed through urine antigen alone (14), culture in
combination with other tests (5), serology (2), culture alone (1), direct fluorescent
antibody of respiratory secretions alone (1) or unknown (1).
•
Outcomes – Hospitalization was required for 22 of 23 cases with this information
available; 18 of 20 cases (90 percent) with information available had X-ray confirmed
pneumonia; no fatalities were attributed to Legionella infection.
Summary
In 2001, there were 24 cases of legionellosis reported in Illinois. Three-quarters of the
cases had pre-existing medical conditions. No outbreaks were detected in 2001.
Suggested readings
Benin AL, Benson RF, Besser RE. Trends in Legionnaires disease, 1980-1998: Declining
mortality and new patterns of diagnosis. Clin Inf Dis 2002;351039-46.
Muder RR, Yu VL. Infection due to Legionella species other than L. pneumophila. CID
2002:35:990-8.
Murdoch DR. Diagnosis of Legionella Infection. CID 2003;36:64-9.
112
113
Lyme disease
Background
Lyme disease is a tickborne disease caused by the bacterium Borrelia burgdorferi sensu
lato. The reservoir is the black-legged tick (Ixodes scapularis), commonly called the “deer tick.”
Human disease is thought to be primarily caused by nymphal tick bites, usually in late spring or
summer. Babesiosis and ehrlichiosis also are transmitted by the same tick. In the Midwest, wild
rodents and other animals maintain the transmission cycle. Deer are the preferred host of the
adult tick.
Laboratory studies indicate ticks must be attached for > 24 hours for transmission to
humans to occur. Experiments in animals have shown that most often the tick must feed at least
48 hours before the risk of transmission becomes substantial.
Lyme disease is characterized by a rash-like skin lesion (erythema migrans) that may be
followed by cardiac, neurologic and/or rheumatologic involvement. The incubation period for
erythema migrans (EM) ranges from three to 32 days after tick exposure; it is present in 80
percent to 90 percent of case patients. Erythema migrans may be characterized by a homogenous
rash rather than a target appearance because of early presentation for treatment. A study of
culture confirmed Lyme disease cases showed that approximately 59 percent of the rashes were
homogenous and of a median size of 10 cm at three days. Early manifestations include fever,
headache, fatigue, migratory arthralgias and possibly lymphadenopathy. It can take
approximately two to four weeks or longer for antibodies to be detected by blood tests so these
tests are not required for patients diagnosed with EM in the public health surveillance case
definition. The most sensitive diagnostic method for Lyme disease in patients with a clinical
diagnosis of erythema migrans in a study in New York was quantitative PCR on skin biopsy
material followed by two-stage serologic testing of convalescent-phase samples, followed by
conventional nested PCR.
The Infectious Diseases Society of America issued guidelines recommending 14 to 21
days of an oral antibiotic for the treatment of erythema migrans.
Lyme disease surveillance in the United States by CDC began in 1982. There were
17,029 cases of Lyme disease reported in 2001 in the United States, mainly from the Northeast,
mid-Atlantic and north-central regions of the country. At that time, the Lyme vaccine was still
available for use.
Infectious diseases, such as Lyme disease, are often undereported. A study in Wisconsin
showed that only about one-third of the Lyme disease cases were reported to the state. The
annual incidence of Lyme disease from 1992 to 1998 in Wisconsin was nine per 100,000. The
group of passively reported patients did not differ from those identified through medical record
review in gender, age or year of diagnosis. Reported patients were less likely to have early stage
Lyme disease.
In Illinois, a tick collection study of Ixodes scapularis was performed by staff at the
University of Illinois College of Veterinary Medicine in the northern part of the state. Parks in
Ogle and Rock Island counties have dense tick populations. Deer ticks were also found in Cass,
Fulton, Mason and Tazewell counties. The researchers also concluded that tick populations may
be limited to river corridors because much land in Illinois is used for agriculture. Forest suitable
for tick habitat and the presence of forests is limited in much of Illinois.
114
Case definition
The surveillance case definition for Lyme disease in Illinois is the CDC definition: 1)
erythema migrans, or 2) at least one late manifestation (musculoskeletal system, nervous system
or cardiovascular system) and supportive laboratory evidence of infection or laboratory
confirmation, i.e., isolation of B. burgdorferi from a clinical specimen, or demonstration of
diagnostic immunoglobulin M or immunoglobulin G antibodies to B. burgdorferi in serum or
cerebrospinal fluid (CSF). A two-test approach using a sensitive enzyme immunoassay or
immunofluorescence antibody followed by Western blot is required by IDPH for confirmation of
non-EM cases.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 32 (five-year median = 14) (Figure 61).
•
Age – Cases ranged in age from 6 to 76 years of age.
•
Gender – 24 cases (75 percent) were male.
•
Race/ethnicity – 31 cases were white and one had unknown race. One case was Hispanic.
•
Geographic distribution – The exposure locations for the 2001 cases were Carroll County
(2), Grundy County (2), Adams or Pike County (1), Calhoun or Pike County (1), Henry or
Ogle County (1), Ogle County (1) and Whiteside County (1). One case reported an out-ofcountry exposure location. The remaining 22 cases cited exposures in states other than
Illinois (Wisconsin, 16; Connecticut, 1; Kentucky, 1; Pennsylvania, 1; Rhode Island, 1;
and Virginia, 1).
•
Symptoms – Qualifying manifestations were EM (21), rheumatologic signs (14) and
neurologic signs such as Bell’s palsy (4) or lymphocytic meningitis (2).
•
Past incidence – In Illinois, reported Lyme cases for previous years are as follows: 1991
(51), 1992 (41), 1993 (19), 1994 (24), 1995 (18), 1996 (10), 1997 (13), 1998 (14), 1999
(17), 2000 (35) and 2001(32).
Summary
For the 32 cases reported in Illinois residents during 2001, EM was the most common
qualifying manifestation. Lyme disease cases peak in summer months.
Suggested readings
Guerra M, Walker E et al. Predicting the risk of Lyme disease: Habitat suitability for
Ixodes scapularis in the North Central United States. Emerg Inf Dis 2002;8(3):289-97.
Nadelman RB. Recognition and treatment of erythema migrans: Are we off target? Ann
Int Med 2002; 136(6):477-79.
Naleway A, Belongia EA et al. Lyme disease incidence in Wisconsin: A comparison of
state-reported rates and rates from a population-based cohort. Am J Epidemiol 2002;155:1120-7.
115
Nowakowski J, Schwartz I et al. Laboratory diagnostic techniques for patients with early
Lyme disease associated with erythema migrans: A comparison of different techniques.
CID2001;33:2023-7. Steere AC. Lyme disease. NEJM 2001;345(2):115-25.
116
Malaria
Background
Malaria is a very important global parasitic disease. It is endemic in more than 100
countries. The incubation period may range from seven days to 10 months. Persons with malaria
experience a febrile illness and may have headache, back pain, vomiting, diarrhea, myalgia,
cough and increased sweating. Four species of Plasmodium (Plasmodium vivax, P. falciparum,
P. malariae and P. ovale) cause disease in people. P. vivax malaria is the most common form.
Identification of the species is important because treatment can differ. For example, disease
caused by P. falciparum has a more serious prognosis and must be treated differently. Untreated
P. falciparum can progress to coma, renal failure, pulmonary edema and death. The majority of
fatal cases in the United States are due to not using correct chemoprophylaxis, incorrect initial
chemotherapy and delays in malarial diagnosis. One of the most important diagnoses to consider
in recent travelers with fever is malaria. Imported malaria cases occur in Illinois when someone
with the disease immigrates to the United States or when someone who travels overseas uses
inadequate chemoprophylaxis. Persons traveling to malarious areas should take recommended
chemoprophylaxis regimens and use appropriate personal protective measures against mosquito
bites (mosquito netting and repellents). The risk of malaria depends on geographic location of
travel, urban vs. rural stay, type of accommodations, duration of stay, time of the year,
destination, elevation and compliance with preventive measures. The highest risk of malaria is
for travelers to sub-Saharan Africa, Papua New Guinea and the Solomon Islands. About 90
percent of P. falciparum infections are acquired in Africa. More than 70 percent of P. vivax
infections are due to exposures in Asia or Latin America.
In the United States, malaria is transmitted predominantly by the bite of an infective
female anopheline mosquito in travelers overseas. Other less common methods would include
infected blood products, congenital transmission or local mosquito borne transmission. The
estimated incidence of malaria transmission by blood transfusion is less than one case per million
units collected. From 1992 to 2002, 10 outbreaks involving 17 cases of probable locally acquired
mosquito-borne transmission occurred in the U.S.; none were in Illinois.
A study of the malaria surveillance system using cases from 1998, 2000 and 2001 showed
that 34 percent of malaria cases identified in a hospital discharge database in Illinois were
reported to IDPH. Less than half (41 percent) of all reported cases in Illinois had laboratory
slides forwarded to IDPH for species identification, required under, communicable disease rules.
The gold standard for diagnosis is the blood smear.
For the 10-year period, 1992 to 2001, there were 629 malaria cases reported in Illinois, all
acquired outside the United States. Approximately one-third lived in Chicago. Most cases were
acquired in Africa, Central America and India.
During 2001, 1,544 malaria cases were reported in the United States. Most cases were
imported, with twice as many cases occurring among United States. residents traveling to
malarious areas as occurred among foreign residents traveling to, and diagnosed in the United
States. Nationally, P. falciparum cases increased by 13 percent as compared to 2000 and P. vivax
decreased by 26 percent. Seventy-seven percent of infections acquired in Africa were P.
falciparum and 11 percent were P. vivax. Sixty-eight percent of national cases were acquired in
117
Africa, 18 percent in the Americas and 12 percent in Asia. Seventy-four percent of cases
occurred in U.S. residents and 26 percent in residents of other countries. Two deaths from
malaria following inappropriate malaria chemoprophylaxis were reported by CDC. These
patients were taking chloroquine for travel to sub-Saharan Africa, where antimalarial resistance
to this drug is common. Chloroquine is only effective for malaria prophylaxis in a few areas of
the world. Illinois had the seventh highest number of cases per state in 2001.
Case definition
Illinois uses the CDC’s case definition. A confirmed case is a person with an episode of
microscopically confirmed malaria parasitemia in any person (symptomatic or asymptomatic)
diagnosed in the United States regardless of whether the person experience previous episodes of
malaria while outside the country.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 71, all of which were imported from
outside the United States. (Five-year median = 72) (Figure 62). There were individual
surveillance report forms for 51 of these cases. A U.S. address was reported by 43 of the
cases.
•
Age – Peak occurred in the 40- to 49-year-old age group; the mean age was 36 (Figure
63).
•
Race/ethnicity – 9 percent were Asian, 61 percent were African American and 30 percent
were white; 7 percent were Hispanic. There were significantly higher proportions of
Asians and African Americans with malaria compared to their representations in the
Illinois population and significantly lower proportions of whites and Hispanics with
malaria compared to their representation in the Illinois population.
•
Seasonal variation – Cases of malaria were reported throughout the year (Figure 64).
•
Speciation – The malaria species identified in the reported cases were falciparum (29
cases, 41 percent), vivax (14 cases, 10 percent), malariae (2 cases, 3 percent), ovale (0),
mixed (0) and unknown (37).
•
Treatment/outcomes – 28 (57 percent) were hospitalized. The 29 P. falciparum cases
were treated with the following medications: chloroquine (1), mefloquine (2),
primaquine (1), quinine/quinidine (7), quinine/quinidine and tetracycline (1),
quinine/quinidine and tetracycline/doxycycline (7), primaquine and tetracycline/
doxycycline (1), chloroquine, doxycycline and other (1), and unknown (8). One fatality
from malaria was reported. One cerebral malaria was reported.
•
Risk factors – The major risk factor is travel outside the United States (Figure 65).
Specific information was available for 47 of the 2001 cases. In southeast Asia, China was
the only country visited by a malaria case prior to illness. On the Indian subcontinent,
cases traveled to India (3), Pakistan (2) and Indonesia (1). In Africa, the following
countries were visited: Nigeria (16), Ghana (6), Uganda (3), Cameroon (1), Kenya (1),
Benin (1), Burkina Faso (1), Sudan (1), South Africa (1), West Africa (1), Cameroon and
Republic of Congo (1), multiple countries (1), and Africa, not further specified (1). In
South America, one case visited Ecuador. Four cases visited multiple countries on
different continents, which included Brazil, England, Germany, Italy, Kenya, Liberia and
118
South America (country not specified),
Of the 16 cases reporting travel to Nigeria, 11 were infected with P. falciparum, three
with P. vivax and two were not speciated. Five of six cases who visited Ghana had P.
falciparum and one had P. malariae. The three cases reporting travel to India were
infected with three different species: P. vivax (1), P. falciparum (1) and P. malariae (1).
Cases provided the following reasons for travel overseas: visiting relatives (29),
missionary work (6), tourism (2), refugee (2), Peace Corps (2), student or teacher (1),
business (1) and other (3).
•
Malaria prophylaxis was reported by 20 (43 percent) cases. Cases indicated taking the
following medications: chloroquine (4), mefloquine (4), chloroquine plus another drug
(3), other drugs (5) and unknown type (4). Among those who indicated they traveled to
visit relatives, 35 percent took prophylaxis while 56 percent of those traveling for other
reasons took prophylaxis. Individuals who are visiting relatives who may be in the
country of their birth may be less likely to assume they need to take prophylaxis.
Past infection – 16 cases (36 percent) reported a history of malaria in the last 12 months.
Summary
There were 71 reported cases of imported malaria identified in Illinois in 2001, which
was similar to the median number of cases in the previous five years. African Americans and
Asians had a higher proportion of individuals with malaria than their representation in the Illinois
population. Thirty-six percent of Illinois cases did not have a species identified as compared to
12 percent of nationally reported cases. Laboratories should forward blood smears to the IDPH
laboratory for verification of species. Laboratories should be thorough in identifying the species
of this parasite because treatment differs by species (e.g., P. vivax and P. ovale require additional
treatment with primaquine to prevent relapses).
Suggested readings
Kain KC, Shanks GD, Keystone JS. Malaria chemoprophylaxis in the age of drug
resistance. I. Currently recommended drug regimens. CID 2001; 33: 226-34.
MMWR. Local transmission of Plasmodium vivax malaria-Virginia, 2002. MMWR
2002; 51(41):921-923.
MMWR. Summary of notifiable diseases-United States, 2001. MMWR
2003;50(53):xviii.
MMWR. Malaria surveillance-United States, 2001. MMWR 2003; 52(SS-5): p. 1-16.
MMWR. Malaria deaths following inappropriate malaria chemoprophylaxis-United
States, 2001. MMMWR 2001; 50(28):pp.597-599.
Mungai M, Tegtmeier G et al. Transfusion-transmitted malaria in the United States from
119
1963 through 1999. NEJM 2001;344 (26):1973-78.
Ryan ET, Wilson ME, Kain KC. Illness after international travel. NEJM
2002;347(7):505-16.
120
121
Measles
Background
Measles is a highly communicable viral disease; humans are the only natural host for the
infection. Transmission most commonly occurs through airborne spread or through direct contact
with nasal or throat secretions of infected people. The incubation period is about 10 days, but
varies from seven to 18 days. Infected individuals show fever, conjunctivitis, coryza, cough and
Koplik’s spots on the buccal mucosa, along with a rash that appears on the third to seventh day.
The disease can be prevented by proper immunizations. A two-dose vaccination schedule is
recommended in the United States, one at 12-15 months and one at school entry (4-6 years) or by
11-12 years. Sustaining high levels of vaccination is important to limit indigenous spread of
measles from cases imported into the United States.
Nationally, there were 116 cases reported to CDC; 54 were imported and 62 were
indigenous. Of the 62 indigenous cases, 25 were import-linked, 12 were imported virus cases
(cases that cannot be linked epidemiologically to an imported case, but for which imported virus
has been isolated from the case or from an epidemiologically linked case); and 25 were unknown
source cases. The United States recorded 10 measles outbreaks (clusters of three or more cases)
in 2001. In the United States, about one or two measles deaths will occur among every 1,000
reported cases. The risk of death and other complications is higher among young children and
adults.
Case definition
A confirmed case in Illinois is one that meets the CDC definition, i.e., a case that is
laboratory confirmed, or that meets the clinical case definition and is epidemiologically linked to
a confirmed case. Laboratory confirmation consists of 1) isolation of measles virus from a
clinical specimen, or 2) significant rise in measles antibody level by any standard serologic
assay, or 3) positive serologic test for measles IgM antibody. The clinical case definition is an
illness characterized by a generalized rash lasting > three days, and a temperature of > 101 F,
and a cough or coryza or conjunctivitis.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 3 (See Figure 66).
•
Age – The cases included a 27-year-old mother and her 9-month-old child returning from
Korea. The parent was hospitalized for one day. The third case was an 11-month-old
Chinese adoptee after an outbreak in China.
•
Race/ethnicity – All cases were Asian, non-Hispanic.
•
Diagnosis – All three cases were IgM positive for measles and the 9-month-old also had a
positive PCR test.
•
Geographic distribution – Cases were from Cook and McHenry counties.
Summary
Three cases of measles were reported in Illinois in 2001.
122
Suggested reading
Drutz JE. Measles: Its history and its eventual eradication. Sem Ped Inf Dis
2001;12(4):315-22.
MMWR. Summary of notifiable diseases-United States 2001. MMWR
2003;50(53):p.xviii-xix.
MMWR. Measles-United States, 2000. MMWR 2002;51(6):120-3.
123
Mumps
Background
Mumps is transmitted by droplet spread and by direct contact with the saliva of an
infected person. The incubation period is 12 to 25 days. This viral disease is characterized by
fever and swelling and tenderness of salivary glands. Orchitis may occur in males and oophoritis
in females. Winter and spring are the times of increased occurrence. Vaccination can prevent
mumps. In 2001, 266 mumps cases were reported to CDC.
Case definition
A confirmed case in Illinois is one that meets the CDC case definition: a clinically
compatible illness that is laboratory confirmed, or that meets the clinical case definition and is
epidemiologically linked to a confirmed or probable case. A laboratory-confirmed case does not
need to meet the clinical case definition. The laboratory confirmation may consist of 1) isolation
of mumps virus from a clinical specimen, or 2) a significant rise in mumps antibody level by a
standard serologic assay, or 3) a positive serologic test for mumps IgM antibody. The clinical
case definition is an illness with acute onset of unilateral or bilateral tender, self-limiting
swelling of the parotid or other salivary gland, lasting > 2 days, and without other apparent cause.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 21 (Figure 67).
•
Age – Median age was 15 years (range was 1 year to 59 years).
•
Gender – 57 percent were female.
•
Race/ethnicity – 67 percent were white (14 cases), 14 percent were African American (3),
9 percent (2 cases) were Asian and the rest were unknown or other races. Four cases
reported Hispanic ethnicity.
•
Geographic distribution – Cases resided in 12 counties (Cook, DeKalb, DuPage, Kane,
Lake, Madison, McLean, Morgan, Tazewell, Vermilion, Wayne and Will).
•
Seasonal variation – Cases occurred from January through December.
•
Immunization status – 13 cases were age-appropriately vaccinated with two vaccines;
four cases had unknown vaccination status; and four cases had no vaccine history but
were ages 46-58 years old.
Summary
The median age of the 21 reported mumps cases in 2001 was 15 years. Half reported
being appropriately immunized. Mumps increased in 2001 over the previous year (6).
124
Suggested readings
MMWR. Summary of notifiable diseases-United States, 2001. MMWR 2003;50(53):
p.xix.
125
Pertussis
Background
Pertussis is caused by Bordatella pertussis and is characterized by a paroxysmal cough
that can last several weeks. Pertussis should be considered in adolescents and adults especially if
the cough is associated with vomiting or gagging or persists for more than two weeks. Pertussis
in adults may be missed because symptoms may be atypical, and nasopharyngeal cultures are
rarely positive if taken during the first seven days of illness. Transmission is by contact with
secretions from respiratory mucous membranes of infected persons. The incubation period is
from six to 20 days. Peaks in pertussis incidence have occurred every three to four years in the
United States. This may be due to an accumulation of susceptibles in populations. Pertussis is a
notifiable disease in every state in the United States. Active immunization with five doses of
vaccine at 2, 4, and 6 months, at 12-15 months and at school entry can prevent this disease. Since
1995, the percentage of those receiving more than three doses of a pertussis-containing vaccine
has been greater than 94 percent among United States residents ages 19-35 years.
Pulsed-field gel electrophoresis (PFGE) can be used to discriminate between isolates of
B. pertussis. A study in Cincinnati, Ohio, from 1989 to 1996 showed that six PFGE profiles
accounted for 79 percent of isolates during the study period. Most isolates from household
members had identical PFGE profiles, indicating that transmission among household members
occurs.
A total of 7,580 pertussis cases were reported to CDC from states. Of these cases, 22
percent were in infants younger than 6 months of age (too young to have received three doses of
vaccine); 3 percent occurred among children ages 6-11 months; 13 percent in 1-to 4- year-olds;
10 percent among 5- to 9-year olds; 30 percent among 10-19 year olds; 22 percent in those older
than 20 years of age. Vaccine-induced immunity may wane five to 10 years after pertussis
vaccination. From 1997 through 2000, the average annual incidence rate of pertussis cases
reported to CDC was 2.7 per 100,000.
In Minnesota, the annual incidence of pertussis in a managed care association was 507
per 100,000 for 1995 and 1996. In a Canadian study, one in five adolescents or adults with
prolonged cough had laboratory evidence of pertussis. The mean duration of cough was eight
weeks. Almost half of laboratory confirmed cases in this study experienced vomiting after the
coughing episodes. Complications were more common in adults than in adolescents. The
secondary attack rate in family members older than 11 years of age was 11 percent. The main
sources of infection in adolescents was schoolmates or friends and, in adults, it was their children
or coworkers.
An epidemiologic study was conducted in Illinois by Mark Dworkin, M.D., state
epidemiologist, with pertussis data from 1996 through 2002. Demographics of cases (N=1,547)
included 724 (46.8 percent) who were younger than one year of age (median age 7 years). Fiftyfive percent were female. In this study, race distribution was 1,160 (75 percent) white and 124
(8 percent) African American; 13 percent were Hispanic. Among 442 cases with such
information, 192 (43 percent) were hospitalized. Hospitalization was most frequent among
children (more than 75 percent of hospitalized cases were younger than 10 years of age). Cases
who were younger than 1 year of age were associated with an increased risk for hospitalization
126
(relative risk [RR] = 1.9, 95% coincidence intervals [95% CI] 1.6 – 2.3). Three infants died
(ages 2 to 5 months) from pertussis from 1996 through 2002. A macrolide antibiotic was the
initial choice of treatment for 467 (73 percent) cases (N=650 cases with such information).
Among others with prescription information, a macrolide was prescribed as a second treatment to
91 (76 percent) cases. Among 106 cases with serology testing, 65 (60%) cases had positive
results reported. PCR testing was performed on specimens from 173 (11.2%) cases; 84 (49
percent) of these were positive. Among 111 cases with PCR and culture results, patients who
were culture-positive were more likely to have a positive PCR result (RR=3.0, 95% CI 2.2 – 4.3);
the median time from onset of illness to PCR testing was longer for cases who tested PCR
negative (14.8 days vs. 25.8 days). Cases with nasopharyngeal swab for PCR collected less than
22 days after date of onset of illness were more likely to have a positive result (RR 1.7, 95% CI
1.1- 2.6).
Case definition
The case definition for pertussis in Illinois is a clinically compatible illness that is
laboratory confirmed or epidemiologically linked to a laboratory-confirmed case. Laboratory
confirmation is through culture of B. pertussis from a clinical specimen. A clinically compatible
illness is a cough lasting at least two weeks with one of the following: paroxysms of coughing,
inspiratory whoop or post-tussive vomiting (without other apparent causes) or greater than two
weeks of coughing in a person in an outbreak setting. A confirmed case is defined as a cough
illness of any duration in any person with isolation of B. pertussis or a case that meets the clinical
case definition and is confirmed by polymerase chain reaction or by epidemiologic linkage to a
laboratory-confirmed case. A probable case meets the clinical case definition but is not
laboratory confirmed or epidemiologically linked to a laboratory-confirmed case.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 194 (five-year median = 151); the one-year
incidence rate was 1.6 per 100,000. There was an outbreak of pertussis (63 persons) in
adults residing in a rural county.
•
Age – 54 percent occurred in those younger than 5 years of age (Figure 68); 24 percent
(46 of 191 reported cases) occurred in those over 19 years of age, which is similar to the
situation in the United States as a whole.
•
Gender – Females comprised 60 percent of cases.
•
Race/ethnicity – 78 percent were white, 7 percent were African American, 9 percent were
other and 6 percent were unknown; 16 percent reported Hispanic ethnicity.
•
Seasonal variation — Cases increased in October, November and December during the
outbreak that occurred in Coles County (Figure 69).
•
Past incidence – The number of reported cases of pertussis declined between 1950 and
2001 (Figure 70).
127
Summary
There were 194 cases of pertussis reported in Illinois in 2001 including one large
outbreak in Coles County. The highest incidence occurred in those younger than 5 years of age.
Thirty-eight percent of cases were outbreak-related.
Suggested readings
Bisgard KM, Christie CDC et al. Molecular epidemiology of Bordatella pertussis by
pulsed-field gel electrophoresis profile: Cincinnati, 1989-1996. JID 2001;183:1360-7.
DeSerres G et al. Morbidity of pertussis in adolescents and adults. J Inf Dis
2000;182:174-9.
Edwards KM. Is pertussis a frequent cause of cough in adolescents and adults? Should
routine pertussis immunization be recommended? CID 2001;32:1698-9.
MMWR. Summary of notifiable diseases-United States, 2001. MMWR 2003;50(53):p.
xix.
MMWR. Pertussis-United States, 1997-2000. MMWR 2002; 51(4):73-76.
Senzilet LD et al. Pertussis is a frequent cause of prolonged cough illness in adults and
adolescents. CID 2001;32:1691-7.
Strebel P et al. Population-based incidence of pertussis among adolescents and adults,
Minnesota, 1995-1996. JID 2001;18:1353-9.
Yih WK et al. The increasing incidence of pertussis in Massachusetts adolescents and
adults, 1989-1998. J Inf Dis 200;182:1409-16.
128
129
Rabies
Background
Rabies is a disease that primarily affects wildlife populations. It is a neurologic illness
that follows infection with a rhabdovirus. It produces encephalitis and typically progresses to
death. Transmission of rabies to humans results from the bite of a rabid animal or from contact
between the saliva of a rabid animal and a mucous membrane or wound. The incubation period is
usually three to eight weeks. Symptoms may include fever, anxiety, malaise, and tingling and
pruritus at the bite site. Neurologic signs, beginning two to 10 days later, may include
hyperactivity, paralysis, agitation, confusion, hypersalivation and convulsions. The paralytic form
must be differentiated from Guillain Barré syndrome. After two to 12 days, the patient may go
into a coma and experience respiratory failure. Diagnosis is highly reliant on consideration of this
rare disease and appropriate testing.
In 2001, the United States and Puerto Rico reported one case of human rabies and 7,437
cases of animal rabies. The strain of rabies virus in the person was consistent with that found in
rabid Philippine dogs. The person had previously traveled to the Philippines but had experienced
no known dog bite while there according to friends and relatives. Since 1990, 24 of 26
indigenously acquired human rabies cases were associated with bat variants but only two persons
reported a definite history of bite. The strain of rabies virus in these human cases is most often
found in the silver-haired and eastern pipistrelle strains.
Wild animals accounted for 93 percent of the animal cases reported in the United States;
the top three species with rabies were the skunk, raccoon and bat. Cases of rabies in bats were up
3 percent from 2000. The most commonly identified rabid bat in the United States was the big
brown bat. The peak of bat rabies in the United States is in August. There is an extensive oral
rabies baiting program in the United States. Only one rabid raccoon was identified in Ohio where
an ongoing oral rabies vaccination program for raccoons and fox is ongoing. One way to control
rabies in wildlife hosts, such as raccoons or fox, is to use oral rabies vaccine. The cost of
distributing baits in Ohio from 1997 to 2000 was $102 to $261 per kilometer squared. Only one
small rodent, a chipmunk, was identified with rabies in the United States, in Maryland. In
Arizona, there was spillover of bat rabies into skunks, with 19 of 59 skunks identified with the
bat variant of rabies.
In Illinois, the skunk and the bat are the main wildlife reservoirs of rabies virus. Illinois
was one of nine states that reported rabies in bats but not in terrestrial animals in 2001. The last
human case of rabies in Illinois was reported in 1954.
After a provoked bite, healthy dogs, cats and ferrets can be observed for 10 days rather
than be euthanized and tested for rabies. Wild animals that expose a person should be tested for
rabies if the animal is available for testing. However, rabbits and small rodents rarely are
identified with rabies and testing of them is optional. The need for testing exotic pets, captive
animals and farm animals that bite a person are evaluated on a case-by-case basis by local animal
control personnel and the staff of the Illinois Department of Agriculture. The approved animal
rabies vaccines are listed in the Compendium of Animal Rabies Prevention and Control
(reference in suggested readings list).
A study of rabies post-exposure prophylaxis (PEP) in Florida showed that three-quarters
of exposures resulting in prophylaxis were due to bites and two-thirds of exposures were from
domestic animals. Twenty-two percent of PEP administrations were inappropriate according to
130
standard guidelines. From 1993 to 1998 in New York, raccoons were the most common species
with rabies and 18,238 persons were given rabies PEP in the state.
Pre-exposure rabies vaccination may be recommended for some travelers, persons who
work with animals and laboratory workers. In a study in California, about 85 percent of
veterinary respondents reported being vaccinated but only 17 percent of staff members were
vaccinated.
Case definition
The case definition for human rabies is a clinically compatible illness that is laboratory
confirmed. Laboratory confirmation is through detection by direct fluorescent antibody (DFA) of
viral antigens in a clinical specimen (preferably the brain or the nerves surrounding hair follicles
in the nape of the neck), or isolation of rabies virus from saliva or cerebrospinal fluid (CSF), or
identification of a rabies-neutralizing titer of greater than 1:5 in the serum or CSF of an
unvaccinated person.
Descriptive epidemiology
•
Number of animals submitted for rabies testing in Illinois in 2001 – 4,280; 69 did not
meet criteria established by the testing laboratories (Illinois Department of Agriculture
and IDPH). Examples of unsatisfactory specimens are those determined to be too
decomposed or too damaged to test. Twenty-four brains were DFA positive; all positive
animals were bats (Table 9). Trends in animal rabies testing in Illinois are shown in
Figure 71.
•
Exposures to rabid bats – There were 24 rabid bat situations.
<
In 20 of the 24 rabid bat situations, no human exposures sufficient to result in the
need for rabies post-exposure occurred. In the other four rabid bat situations,
humans were exposed. In one situation, two family members were bitten by the
rabid bat and were given rabies PEP. In the second situation, a person stepped on
a bat and was bitten and received rabies PEP. In the third situation, a veterinarian
was collecting a bat from a home and the bat spit into his eye. Although the
veterinarian was pre-exposure vaccinated for rabies, he was recommended for
rabies post-exposure prophylaxis which he chose not to receive. In the fourth
human exposure situation, five family members in an apartment received rabies
post-exposure prophylaxis when a rabid bat was found in their home.
<
Domestic animals were either exposed or possibly exposed in four of the
situations (Table 10).
<
Condition of bat when found – Four of the rabid bats were down and unable to fly,
one was found dead, two were described as aggressive, and the behavior of the
other 17 was not described.
•
Testing of bats – Bats accounted for all of the confirmed rabid animals in 2001 (positivity
rate = 3 percent).
<
Geographic distribution – The rabid bats were widely dispersed across the state:
Lake (5), Winnebago (3), Cook (2), St.Clair (2), Vermilion (2), and one each in
Bond, Calhoun, Christian, Coles, Effingham, Greene, Jackson, Kane, McHenry
131
•
and Tazewell counties.
<
Speciation – Six of the rabid bats were speciated; four were identified as big
brown bats and two as small brown bats. Of the 170 bats submitted for speciation
and testing negative for rabies in 2001, 130 were identified as big brown bats and
31 were identified as little brown bats; six were identified as silver-haired bats,
two as red bats and one as another type of bat.
<
Seasonal variation – Figure 72 shows bats submitted for testing by month in 2001.
Bats submitted for rabies testing increased in summer months.
Testing of skunks – Rabies testing was performed on 82 skunks in 2001 compared to 62
in 2000. At least one skunk from each of 26 Illinois counties was tested; no skunks were
tested in 76 counties. As was the case with bats, the number of skunks tested increased
between 2000 and 2001.
To maintain adequate surveillance in the state, the testing of skunks, the main terrestrial
animal reservoir, must be maintained. Negative test results of wild terrestrial mammals is
one factor used to determine whether rabies PEP is recommended in cases of stray dog
and cat bites. A June 2000 memo to local health departments and animal control
administrators encouraged submission of skunks even if there was no human or domestic
animal exposure. This may have stimulated increased submission of skunks for testing in
2000 and 2001.
•
•
Figure 73 shows the number of rabid skunks found in Illinois and the road kill index from
1975 through 2001. The road kill index is calculated by the Illinois Department of Natural
Resources as a measure of changes in the skunk population size. When the road kill index
increases, the skunk population is increasing and is believed to indicate that conditions
are suitable for a rabies epizootic in skunks. This occurred in the late 1970s and early
1980s, when the road kill index and the rate of skunks testing positive increased.
Rabies positivity rate – Table 11 shows the rabies positivity rate in different species of
animals in Illinois from 1971 to 2001. This information can be useful in explaining why
rabies PEP is not recommended for the large majority of mouse, rat or squirrel bites. No
rats, mice or squirrels have been identified with rabies in Illinois during the past 30 years.
Because skunks and bats with rabies are identified almost every year in Illinois, rabies
PEP is recommended for exposures for these animals and other wild animals unless they
can be tested and are negative for rabies. When comparing the positivity rates for
cumulative 1971-2001 data vs. 1991-2001 data, the percentage of skunks positive for
rabies declined dramatically and the percentage of positive bats stayed very constant.
Past incidence – Figure 74 shows animal rabies in the state since 1970. Two peaks of
rabies, 10 years apart, occurred in the state: one in 1971 and the other in 1981. No peaks
have occurred since that time.
Summary
Bats were the only species identified with rabies in Illinois in 2001. Testing of skunks for
132
rabies has declined in Illinois thereby decreasing the reliability of surveillance of the terrestrial
animal reservoir in the state. This is the third consecutive year where no rabid skunks have been
identified in the state. Local jurisdictions are encouraged to increase testing of skunks for rabies.
There have been no human rabies cases in Illinois since 1954. Epizootic raccoon rabies was
identified in northeastern Ohio in past years but has been controlled through oral rabies baiting
programs, slowing the westward progression of this public health problem.
Suggested readings
Chang H-GH, Eidson M et al. Public health impact of reemergence of rabies, New York.
Emerg Inf Dis 2002;8(9):909-914.
Conti L, Wiersma S, Hopkins R. Evaluation of state-provided postexposure prophylaxis
against rabies in Florida. South Med J 2002;95(2):225-30.
Foroutan P, Meltzer MI, Smith KA. Cost of distributing oral raccoon-variant rabies
vaccine in Ohio: 1997-2000. JAVMA 2002;220(1):27-32.
Krebs JW, Noll HR, Rupprecht CE. Rabies surveillance in the United States during
2001. JAVMA 2002;221(12):1690-1701.
Messenger SL, Smith JS, Rupprecht CE. Emerging epidemiology of bat-associated
cryptic cases of rabies in humans in the United States. CID 2002;35:738-47.
NASPHV. Compendium of animal rabies prevention and control, 2003. JAVMA
2003;222(2):156-161.
Trevejo RT. Rabies preexposure vaccination among veterinarians and at-risk staff.
JAVMA 2000;217(11):1647-50.
133
`Table 9. Rabid animals found in Illinois, 2001
Species
Total number
suitable for testing
Total positive
% positive
Bat
848
24
3
Cat
1,149
0
0
46
0
0
1,480
0
0
Coyote/fox
20
0
0
Ferret
25
0
0
Horse/donkey
23
0
0
Opossum
58
0
0
Raccoon
209
0
0
Rodents/lagomorphs
254
0
0
6
0
0
Skunk
82
0
0
Other*
11
0
0
4,211
24
-
Cattle/buffalo
Dog
Sheep/Goats
TOTAL
*Other species include deer, mink, shrew, sugar glider and weasles.
Source: Illinois Department of Public Health, 2002
134
Table 10. Animals positive for rabies (all bats) in Illinois and the type of exposure, 2001
Date
Human exposure?
Animal exposure?
April
bite to child and father
none
April
persons stepped on downed bat and was bitten
none
May
bat spit at veterinarian’s face when he was collecting bat
none
June
found on sidewalk; no exposure
none
July
sick bat found on porch; no human exposure
none
July
bat found in room with young children
none
July
bat found in home but no significant exposure
none
July
none
unknown
July
aggressive bat; no exposure
one dog bitten
August
bat found in yard; no exposure
none
August
bat found downed in home; no exposure
none
August
aggressive bat hanging on house; no exposure
none
August
none
unknown
August
none
none
August
no exposure
dog exposed
August
no exposure
unknown
135
Source: Illinois Department of Public Health, 2002
Table 11. Rabies positivity rate by animal species in Illinois, 1971-2001 vs.1991-2001
1971-2001
Species
# examined
# positive
1991-2001
% positive
# examined
# positive
% positive
Bat
9,442
498
5.3
4,269
196
Cat
40,522
141
0.3
13,524
4
0.03
3,201
214
7.0
769
3
0.4
Dog
40,360
110
0.3
16,815
5
0.03
Fox
1,399
72
5.1
214
0
0
631
22
3.5
172
0
0
Mouse
4,621
0
0
576
0
0
Raccoon
9,040
17
0.2
2,758
0
0
Rat
1,817
0
0
314
0
0
Skunk
7,215
2,526
35
1,047
44
Squirrel
6,609
0
0
1,447
0
Cattle
Horse
136
5.0
4.2
0
Source: Illinois Department of Public Health, 2002
137
Rabies, potential human exposure
Background
Exposures to animals, especially those involving bites or bat exposures, often result in the
need for public health consultation on whether rabies post-exposure prophylaxis (PEP) is needed
for the exposed individual. On April 1, 2001, the reporting of animal bites to public health was
discontinued and replaced with reporting of rabies potential human exposures (RPHE) (Section
690.601 Control of Communicable Disease Code). The purpose of this change in reporting was
to limit the reporting of animal exposures to local public health authorities to situations where
consultation on rabies PEP was needed. All animal bites in Illinois are still reportable to local
animal control for the purposes of following up with the owner of the biting animal. Animal
control authorities are responsible for ensuring that dangerous animals are maintained so that
they cannot injure the public.
Case definition
The definition of an exposed person to be reported covers –
1)
Any contact (bite or non-bite) with a bat, or
2)
Any contact (bite or non-bite) with an animal that subsequently tests positive for
rabies virus infection, or
3)
Anyone who was started on rabies post-exposure prophylaxis, or
4)
Exposure to saliva from a bite, or contact of any abrasion or mucus membrane
with brain tissue or cerebrospinal fluid of any suspect rabid animal. Exposure to
healthy rabbits, small rodents, indoor-only pets or rabies-vaccinated dogs, cats or
ferrets is excluded, unless the exposure complies with the parameters listed above,
or the animal displays signs consistent with rabies.
Descriptive epidemiology
The following information was gleaned from investigation forms obtained during the
surveillance of potential human exposures to rabies in Illinois during 2001. The investigation
forms had questions on demographics, exposure characteristics and rabies post-exposure
treatment information. The type of exposure was characterized as bite, non-bite (scratch or
abrasion), non-bite (contamination of open cuts with saliva or nervous tissue) or non-exposures
(petting, handling or blood contact). The domestic animal’s vaccination status was classified as
not vaccinated; up-to-date on rabies vaccination; previously vaccinated for rabies, but not up-todate; or unknown. Information on whether the animal exhibited signs of rabies such as unusual
aggression, impaired locomotion, paralysis, excess salivation, or no fear of people (in the case of
a wild animal) was requested. For dogs and cats, information on whether the bite was provoked
was requested. Provoked bites were defined as follows: “the bite is considered provoked if the
animal is placed in a situation in which an expected reaction would be to bite, for example,
invading an animal’s territory, attempting to pet or handle and unfamiliar animal, startling an
animal, running or bicycling past an animal, assisting an injured or sick animal, attempting to
separate two fighting animals, trying to capture an animal or removing food, water or other
objects from an animal”. An unprovoked bite was described as a bite for no apparent reason.
Information on whether the person was started on rabies PEP, who made the recommendation
138
and a description of the rabies PEP treatment given was requested. Not all local health
jurisdictions have submitted investigation forms so this is a minimum estimate of the number of
potential human rabies exposures in Illinois.
•
•
•
•
•
•
Number of cases reported in Illinois in 2001 – 96 potential human rabies exposures were
reported for 2001. Only one case was reported between January 1, 2001, and April 1,
2001.
Age – The mean age of those exposed was 32.
Gender – 60 percent of RPHE reports were in males.
Race/ethnicity – 90 percent were white, 6 percent African American and 3 percent Asian.
Seasonal peak – Higher numbers of exposures occurred in the summer months of June
through August, rather than September through December. However, reporting only
started in April 2001.
Geographic location – 35 counties and 33 local health jurisdictions reported at least one
RPHE; 46 percent of exposures took place in urban settings.
Type of exposure
Four types of exposures were listed on the investigation form: bite, non-bite (scratch or
abrasion), non-bite (contamination of open cut with saliva or nervous tissue) or non-exposure
(petting, handling, blood contact). Of the total exposures reported, 72 (75 percent) were reported
to be due to animal bites. Most bites were to the arm or hand (66 percent), followed by leg or
foot (18 percent), head or neck (10 percent) and multiple or other body part (3 percent); five had
unknown bite site. Two percent of persons reported a non-bite (scratch or abrasion) exposure.
Three percent reported saliva or nervous tissue contamination of an open wound. Bats were
found in the room with a sleeping person in 19 (20 percent) exposures and physical contact with
a bat took place in one (1 percent) of exposure. Bats were tested in 10 of the 19 cases where they
were found in a room of the house with a sleeping person. Five tested negative, two tested
positive and two specimens were unsuitable for testing.
Animals causing exposure
Sixty-five percent of animals causing exposure were wild, not domesticated, animals.
The types of animals causing exposures included bat (43 percent), cat (21 percent), dog (14
percent), raccoon (14 percent), opossum (4 percent), unknown canine (1 percent), skunk (1
percent) and groundhog (1 percent); the type of animal was unknown in three situations.
Of the 33 domestic animals exposing persons, 36 percent were owned. Seventy percent
of these animals had an unknown vaccination history, 15 percent were not rabies vaccinated, 12
percent had at least one previous rabies vaccination but were not up-to-date and, 3 percent had
up-to-date rabies vaccinations. Rabies vaccination of dogs is required in Illinois. Only one of
eight owned dogs causing exposures was known to be up-to-date on its rabies vaccinations.
Seventy-five percent of bites from dogs and cats were provoked.
Twenty-six (28 percent) animals, that potentially exposed someone to rabies were
submitted for rabies testing. Sixty (66 percent) animals were not available for confinement or
testing. Of the 27 animals tested for rabies, 67 percent were negative, 22 percent were unsuitable
for testing and 11 percent were rabies positive. All three positive animals were bats. The six
139
specimens that were unsuitable for testing were from bats, opossums and cats. Five of six
persons exposed had to be started on rabies PEP because test results could not be obtained.
For domestic animal exposures, 16 percent were tested for rabies and 13 percent were
confined for observation. The 12 animals were owned by family (33 percent), neighbor (25
percent) or other person (42 percent).
Twenty-two (37 percent) animals were reported to have exhibited signs of rabies. These
included aggression (12), impaired locomotion (4), excess salivation (3), no fear of humans (4)
or other signs (4) (e.g.,death during confinement period, dilated pupils or abnormal eye
movements).
Rabies post-exposure prophylaxis
Initial recommendations about whether rabies PEP was needed for an exposed person
came from the following sources: public health personnel (36 percent), health care provider,
excluding emergency department personnel (42 percent), emergency department personnel (21
percent) or multiple sources (1 percent).
The final recommendation on rabies PEP came from public health personnel (39 percent),
health care provider, other than emergency department personnel (44 percent) or emergency
department personnel (17 percent).
Sixty-seven percent of rabies PEP was given exclusively in an emergency department
setting. Most rabies PEP was paid for by private insurance (71 percent), followed by Medicare
or Medicaid (16 percent), out-of-pocket expense (7 percent), no payment source (4 percent) and
worker’s compensation (2 percent).
Seventy-three (83 percent) people with information available were started on rabies PEP.
Three (4 percent) people recommended for rabies PEP refused to be treated. All three refusers
were exposed to bats. In one case, the person was bitten and the bat was unavailable for testing.
In the second situation, the bat was found in the room with a sleeping person and could not be
tested. In the third situation, the pre-exposure- vaccinated person was exposed to saliva from a
rabid bat after it spit in the person’s eyes. Rabies PEP was completed in 53 (90 percent) of those
in whom it was started. In four people, rabies PEP was not completed because the animal tested
negative; all were bite exposures. (Three were bat exposures and one was a raccoon exposure.)
The rabies PEP recommendation for these four people was made by either emergency department
personnel or by health care providers. In three people, rabies PEP was not completed because it
was refused; in all three cases, the animal was tested negative for rabies.
In 12 of 73 people (16 percent), rabies PEP would not have been indicated according to
public health guidelines. In five of these situations, the animal tested negative for rabies and the
decision about rabies PEP could have been delayed till testing was completed. In two situations,
the victim insisted on rabies PEP in spite of the recommendation that it was not needed. In the
other five situations, the bite from the dog or cat was provoked, there were no signs of rabies
present in the animal, and the animal was not available for testing or confinement. In one
situation, the bite was misclassified as unprovoked. Because of the lack of terrestrial animal
rabies in the last few years in Illinois, no rabies PEP would be recommended if a the dog or cat
bite was provoked and the animal showed no signs of rabies.
For 30 of 51 (59 percent) people completing rabies PEP and with information available,
the ACIP rabies protocol for timing of injection was followed exactly. In 24 (68 percent) of 35
140
persons with information available, the recommended ACIP location of injection was correct.
Errors in protocols included giving vaccine in the gluteal muscle or giving rabies immune
globulin and rabies vaccine in close proximity. Information on both timing and location of
injections for 30 persons completing rabies PEP was available. Rabies PEP was given exactly
according to ACIP guidelines in 13 of 30 (43 percent) individuals. For three individuals, neither
the timing of injections nor the location of injections was according to ACIP guidelines. For six
individuals, only the location was incorrect, and for eight individuals, only the timing was
incorrect.
Only 5 percent of persons exposed had been pre-exposure immunized for rabies.
Summary
Almost three-quarters of the state’s rabies exposures were due to bites. Most bites were to
the hand or arm, which is typical as persons reach to pick up or handle an unfamiliar animal.
Nearly a quarter of reported exposures were from bats found in a room with a sleeping person.
In almost 50 percent of these situations, the bat was not available for testing. Education of the
public and animal control personnel could result in increased submission of bats that have
exposed people in their homes. If the bat tests negative, the person would not need rabies PEP.
The main animal causing potential human rabies exposures was the bat, followed by the
cat, the dog and then the raccoon. This is primarily due to the definition of possible rabies
exposure to a bat. The bat is the only wild mammal where rabies PEP is recommended if a
person is sleeping in a room where a bat is found and it cannot be tested, or if the bat tests
positive.
Almost three-quarters of bites from dogs and cats were provoked. Public education on
avoiding unfamiliar dogs and cats could decrease bites from dogs and cats.
Approximately one-quarter of animals submitted for rabies testing were not suitable for
testing. This may be due to destruction of the brain when the animal was killed or
decomposition of the brain due to slow submission of the specimen or improper shipping to the
laboratory. Decreasing the number of unsatisfactory specimens would lead to fewer people
needing to undergo rabies PEP in the state.
Fifty-nine percent of rabies PEP recommendations were made by emergency department
health care providers or other health care providers. This indicates the importance of providing
health care providers with up-to-date information on rabies incidence in their area and on rabies
PEP recommendations. This information could be easily provided on IDPH Web site.
Some persons recommended for rabies PEP refused treatment. It is important to find out
the reason(s) for their refusals and to provide both oral and written information addressing these
concerns when recommending rabies PEP.
Sixteen percent of rabies PEP given in 2001 would not have been indicated according to
public health guidelines. In some situations, people were started on rabies PEP even though the
animal was available for testing. Health care providers, especially in emergency departments,
should be advised that rabies testing of animals can be completed rapidly at the state laboratories
and, if necessary, emergency testing can be requested for high priority specimens on holidays or
weekends. For emergency testing, health care providers can contact LHD personnel or use the
state emergency phone number. If testing is promptly performed, rabies PEP can be delayed
until testing is completed. In several situations, an exposed person was not recommended for
141
rabies PEP but demanded it anyway. It is possible that additional education could help reassure
such individuals that rabies PEP is not needed. In five situations, a provoked bite from a dog or
cat occurred and the animal exhibited no signs of rabies and yet the person was started on rabies
PEP by the health care provider. In Illinois, there has been no terrestrial animal rabies in three
years. Therefore, no rabies PEP is recommended for dog or cat bites when the bite was provoked
and the animal showed no signs of rabies.
The rabies PEP protocol is provided in “Human Rabies Prevention-United States, 1999.
Recommendations of the Advisory Committee on Immunization Practices (ACIP).” (MMWR
1999;48[RR-1]). In almost a third of cases where rabies PEP was completed, the timing of
injections was incorrect. In almost a third of cases the location of the injection(s) was incorrect.
The ACIP recommendations should be adhered to when administering rabies PEP. It can be
difficult to get exposed individuals to agree to a complicated vaccination schedule but the person
should be informed about the universally fatal nature of rabies and the importance of adhering to
the ACIP schedule.
142
Rocky Mountain spotted fever
Background
Rocky Mountain spotted fever (RMSF) is the most frequently reported fatal tickborne
disease in the United States. RMSF has been reported throughout the continental United States.
The causative agent is Rickettsia rickettsii. Both dogs and humans may experience clinical illness
due to RMSF. In 2001, 695 human cases were reported to the CDC. Most cases are reported
from April through September when the greatest number of Dermacentor ticks are present in the
environment.
Tick vectors include the American dog tick (Dermacentor variabilis) and the lone star
tick (Amblyomma americanum). Only about 1 percent to 5 percent of ticks may be infected with
R. rickettsii in a given area. In order for one of these ticks to transmit the bacteria, it must be
attached for at least four to six hours. The incubation period for RMSF is three to 14 days after a
tick bite. Common presenting symptoms include high fever, severe headache, deep myalgias,
fatigue, chills and rashes. If a skin rash is present, it appears an average of three to five days after
symptom onset. Only about 15 percent of patients have a rash on the first day of illness and less
than one-half develop rash in the first 72 hours after illness. Starting most often on the ankles and
wrists, the rash then appears on the trunk, palms and soles. Patients may also have
gastrointestinal signs (e.g., abdominal pain and nausea) serious enough to lead to erroneous
diagnoses such as appendicitis. The antibiotic of choice for treatment is doxycycline. Older
patients, patients treated with chloramphenicol only, patients for whom tetracycline antibiotics
were not the primary therapy, and patients for whom treatment was delayed more than four days
after the onset of symptoms were at higher risk for death in a CDC study of risk factors reported
in cases from 1981 to 1998. Also, about 65 percent of the cases during this time period were
hospitalized.
Only 3 percent to 18 percent of persons presenting with rash and fever report a history of
tick exposure on the first medical visit. Laboratory abnormalities such as low platelets, elevated
liver enzymes and hyponatremia (low blood sodium level) should also raise the possibility of
RMSF. Treatment should not be deferred while awaiting laboratory confirmation. Such delays
increase the risk of an adverse outcome.
A new CDC investigation form for RMSF was distributed to local health departments for
use in 2001.
Case definition
The case definition for a confirmed case of RMSF in Illinois is a clinically compatible
illness that is laboratory-confirmed. The laboratory confirmation is a four-fold or greater rise in
antibody titer by immunofluorescent antibody (IFA), complement fixation (CF), latex
agglutination (LA), microagglutination (MA) or indirect hemagglutination antibody (IHA) test in
acute and convalescent specimens ideally taken more than three weeks apart; or demonstration of
positive immunofluorescence of a skin lesion or organ tissue, positive polymerase chain reaction
or isolation of R. rickettsii from a clinical specimen. A clinically compatible illness is one
characterized by acute onset and fever, usually followed by myalgia, headache and petechial rash.
A probable case is defined as a clinically compatible case with a single IFA serologic titer of >
143
64 or a single CF titer of >16 or other supportive serology (four-fold rise in titer or a single titer >
320 by Proteus OX-19 or OX-2 , or a single titer >128 by an LA, IHA or MA test).
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 12 probable cases were reported in Illinois.
•
Age – Cases ranged in age from 6 to 75 years of age.
•
Gender – 5 cases were female.
•
Race/ethnicity – 11 cases were white, none Hispanic and one was unknown.
•
Geographic distribution – Sites of tick exposure for the cases were Jefferson County (2),
Bureau County (1), DeWitt County (1), Fayette County (1), Logan County (1), Macoupin
County (1), Marshall County (1), Massac County (1), Randolph County (1), White
County and Winnebago County (1). One case also reported traveling to Wisconsin and
Arkansas within 30 days of onset of symptoms. The locations of Illinois tick exposure in
cases reported in 2001 are shown in Figure 75.
•
Seasonal variation – Onsets of the 12 cases occurred between April and September.
•
Symptoms/outcomes – The following symptoms and signs were reported by five
individuals: myalgia (5), headache (5), fever (4) and rash (4). The other seven cases had a
clinically compatible illness without details on specific symptoms. Five cases were
hospitalized. None of the 12 cases were fatal.
•
Past incidence – Rocky Mountain spotted fever cases reported per year in the state are as
follows: 1991 (5), 1992 (2), 1993 (4), 1994 (11), 1995 (10), 1996 (4), 1997 (3), 1998 (1),
1999 (7), 2000 (5) and 2001 (12).
Summary
Most cases of RMSF occurred in summer months in locations throughout Illinois.
Suggested readings
Holman RC, Paddock CD et al. Analysis of risk factors for fatal Rocky Mountain spotted
fever: Evidence for superiority of tetracyclines for therapy. JID 2001;184:1437-44.
Sexton DJ. Rocky Mountain spotted fever. From: Encyclopedia of arthropod-transmitted
infections of man and domesticated animals. CABI Publishing. 2001.pp.437-442.
Warner RD, Marsh WW. Rocky Mountain spotted fever. JAVMA 2002;221(10):1413-7.
Zaidi SA, Singer C. Gastrointestinal and hepatic manifestations of tickborne diseases in
the United States. CID 2002;34:1206-12.
144
Figure 75. Illinois counties of exposure for 12 Rocky Mountain spotted fever cases, 2001
Source: Illinois Department of Public Health, 2002
145
Rubella
Background
Rubella usually causes a self-limiting disease in adults and children. Transmission is from
direct contact with, or droplet spread of, nasopharyngeal secretions of infected persons. The
incubation period is 12 to 23 days. Rubella can cause a fever and rash along with enlarged lymph
nodes in the head and neck. It is most important because the virus is a teratogen and can produce
congenital anomalies or intrauterine death if a woman is infected during pregnancy.
Immunization against rubella is recommended at 12-15 months of age and a second dose at
school entry or at adolescence. Vaccine should not be given to anyone who is
immunosuppressed, or to pregnant women because it is a live vaccine. Rubella vaccine was
licensed in 1969 and measles-mumps-rubella vaccine was licensed in 1971. The number of
reported rubella cases in the U.S. declined from 56,552 in 1970 to 630 cases in 1985. Rubella
vaccination was mandated for school entry in all states by 1979.
Rubella is one of the most common causes of birth defects in the world. It can result in
spontaneous abortions, stillbirths and congenital rubella syndrome. Congenital rubella syndrome
includes hearing impairment, blindness, heart defects and mental retardation.
In 2001, 23 rubella cases were reported to CDC. Most cases occurred in individuals born
in countries where routine rubella vaccination is not practiced. In 2000 and 2001, 10 mothers of
the 11 children with congenital rubella syndrome were foreign born Hispanics.
Case definition
The clinical case definition for rubella is an illness with acute onset of generalized
maculopapular rash, fever and either arthritis/arthralgia, lymphadenopathy or conjunctivitis. A
confirmed case of rubella is one that is laboratory confirmed or that meets the clinical case
definition and is epidemiologically linked to a laboratory confirmed case.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – Two cases were reported in Illinois.
•
Age – The cases were 21 and 38 years of age.
•
Race/ethnicity: One case was Hispanic.
•
Gender – Both were male.
•
Geographic distribution – Both cases were Cook County residents.
•
Diagnosis – Positive IgM tests were reported eight days after rash onset for one case and
five days after rash onset for the other case.
•
Vaccination status – Both cases had unknown vaccination history.
•
Past incidence – The number of reported rubella cases in Illinois from 1950 to 2001 is
shown in Figure 76.
Summary
In 2001, two rubella case were reported in Illinois.
146
Suggested readings
Cooper LZ. Current lessons from 20th century serosurveillance data on rubella. CID
2001;33:1287.
Dykewicz CA et al. Rubella seropositivity in the United States, 1988-1994. CID
2001;33:1279-86.
MMWR. Summary of notifiable diseases-United States, 2001. MMWR
2003;50(53):p.xx.
147
Salmonellosis (non-typhoidal)
Background
There are more than 2,400 serovars of Salmonella; however, approximately 50 percent of
human cases are caused by three serovars: Salmonella enterica ser Enteritidis, S. ser
Typhimurium, S. ser Newport. Transmission to humans is usually after consumption of
contaminated food products. Raw or undercooked meat, eggs, raw milk and poultry have been
identified as vehicles for Salmonella infection. Fresh produce, such as lettuce, unpasteurized
apple or orange juice or sprouts, also have caused outbreaks.
Hospital and commercial laboratories are required to submit isolates of Salmonella to an
IDPHs laboratory for serotyping. This is necessary to detect increases in specific serotypes.
Identification of serotypes is useful in identifying which patients are likely linked to a common
source of infection. Another way to link Salmonella isolates to a common source is pulse field
gel electrophoresis (PFGE).
Of the 10 diseases/syndromes (those caused by Campylobacter, Cryptosporidium,
Cyclospora, E. coli O157:H7, HUS, Listeria monocytogenes, Salmonella, Shigella, Vibrio and
Yersinia enterocolitica) under active surveillance in the nine federal FoodNet sites, Salmonella
comprised 38 percent of the reported infections in 2001. The incidence rate per 100,000 ranged
from eight to 21 at the nine FoodNet sites in 2001. In the United States, 40,495 cases of
Salmonella were reported to CDC. The number of S. ser. Newport isolates increased from 5
percent to 10 percent between 1997 and 2001. This increase is concurrent with development of
multi-drug resistant S. ser. Newport.
In a study of sporadic S. enterica ser. Enteritidis in Denmark, eggs were found to be the
primary source for human cases. Eating pasteurized eggs was protective against illness. In an
evaluation of S. ser. Enteritidis outbreaks in the United States from 1999 to 2001, it was found
that the most common food vehicle responsible was undercooked and raw shell eggs.
Case definition
The case definition for a confirmed case is isolation of Salmonella from a clinical
specimen. The case definition for a probable case is a person who has a clinically compatible
illness that is epidemiologically linked to a confirmed case, but is not laboratory-confirmed.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 1,383 (Figure 77 for number of cases since
1996). The annual incidence rate for salmonellosis in Illinois in 2001 was 11 per 100,000
population. There were eight confirmed and one suspect foodborne outbreaks of
Salmonella reported in 2001. (See the section of this report detailing foodborne outbreaks
for more details.)
•
Age – Salmonellosis occurred in all age groups (mean age = 28) (Figure 78). However,
the incidence rate was highest in those younger than 1 year of age (67 cases per 100,000
population in females and 94 per 100,000 in males).
•
Gender – 53 percent were female.
•
Race/ethnicity – 85 percent of cases were white, 12 percent African American and 3
148
•
•
•
•
percent other races; 14 percent were Hispanic.
Geographic distribution – The highest mean annual incidence rates for salmonellosis
were scattered around the state (Figure 79). The five counties with the highest mean
annual incidence rates per 100,000 population for salmonellosis from 1997-2001 were
Mason (31), Stephenson (22), Clay (22), JoDaviess (22) and Hardin (21).
Seasonal variation – A peak in salmonellosis cases occurred from May through
September in 2001 (Figure 80).
Serotypes – 89 percent of Illinois’ Salmonella isolates were serotyped. The top 20
serotypes in 2001 are found in Table 12. The three most common serotypes were S. ser.
Typhimurium (285, 23 percent), S. ser. Enteritidis (246, 20 percent) and S. ser. Newport
(121, 10 percent). Serotypes of Salmonella found in Illinois from 1993-2001 are shown in
Table 13.
Risk factors – A history of reptile contact was reported by 64 Salmonella cases in 2001
but a link between the reptiles and transmission of the infection could not be confirmed.
<
Cases reported contact with the following types of reptiles: lizards (25), turtles
(18), snakes (15), not specified (1) and multiple types (5).
<
For those with reported reptile contact, the median age was 8 years; 21 cases were
younger than 5 years of age.
<
Males accounted for almost half (47 percent) of the cases.
<
The two most common species in these cases were Enteritidis (11) and
Typhimurium (10). Salmonella isolates from the subspecies I, II, III and IV have
been associated with reptile contact and, for the 2001 reptile contact cases, the
following serotypes from these groups were identified: Marina (1) and
Mikawasima (1).
Summary
Approximately 1,300 cases of Salmonella were reported in 2001 in Illinois. The one-year
incidence rate of Salmonella for 2001 was 11 per 100,000 population, which is lower than the
average incidence reported at CDC’s FoodNet sites. Several counties in the Rockford region had
a higher incidence of salmonellosis. The mean age for Salmonella cases was 28, although the
incidence was highest in those younger than 1 year of age. Salmonella cases increased in Illinois
during the summer as they did nationally. The percentage of isolates that were serotyped in
Illinois was 89 percent; of these, the most common serotypes were Typhimurium (23 percent),
Enteritidis (20 percent) and Newport (10 percent). S. ser. Newport replaced S. ser. Heidelberg as
the third most common serotype in Illinois compared to 2000. A higher percentage of Illinois
isolates serotyped were S. ser. Enteritidis (20 percent) than FoodNet data for 2001 (13 percent).
Reptile contact was reported in 21 cases younger than 5 years of age. CDC recommends that
households with children younger than 5 years of age not have reptiles as pets.
149
Suggested readings
Bradley T, Angulo F, Mitchell M. Public health education on Salmonella spp. and
reptiles. JAVMA 2001; 219(6):754-5.
Chiu C-H, Wu T-L et al. The emergence in Taiwan of fluoroquinolone resistance in
Salmonella enterica serotype cholerasuis. NEJM 2002;346(6):413-8.
MMWR. Outbreaks of Salmonella serotype Enteritidis infection associated with eating
shell eggs-United States, 1999-2001. MMWR 2003;51(51&52):1149-52.
MMWR. Outbreak of Salmonella serotype Kottbus infections associated with eating
alfalfa sprouts-Arizona, California, Colorado, and New Mexico, February-April 2001. MMWR
2002;51(1): 7-9.
Molbak K, Neimann J. Risk factors for sporadic infection with Salmonella enteritidis,
Denmark, 1997-1999. AJE 2002;156:654-61.
Sanchez S, et al. Animal sources of salmonellosis in humans. JAVMA 2002;221(4):49297.
Van Duynhoven YTHP. et al. Salmonella enterica Serotype Enteritidis phage type 4b
outbreak associated with bean sprouts. Emerg Inf Dis 2002:8(4):440-43.
150
Figure 79. One-year salmonellosis incidence rates for Illinois, 1997-2001
Source: Illinois Department of Public Health, 2002
151
Table 12. Top 20 Salmonella serotypes in Illinois, 2001
Serotype
Frequency
Serotype
Frequency
Typhimurium
285
Saint-paul
22
Enteritidis
246
Javiana
17
Newport
121
Branderup
16
Heidelberg
66
Montevideo
16
Muenchen
42
Hartford
15
Berta
41
Uganda
15
Infantis
35
Agona
14
Oranienberg
28
Poona
12
Java
24
Senftenberg
12
Thompson
24
Anatum
10
Source: Illinois Department of Public Health, 2002
152
Table 13. Frequency of Salmonella serotypes in Illinois, 1993-2001
Serotype
1993
1994
1995
1996
1997
1998
1999
2000
2001
Abaetetuba
0
1
1
0
0
0
0
0
0
Aberdeen
0
0
0
0
0
0
0
1
0
Abony
0
1
0
0
0
0
0
0
0
Adelaide
7
10
10
1
3
2
3
1
4
Agbeni
0
1
4
0
0
0
0
0
0
Agona
57
65
42
38
58
129
48
27
14
Alachua
1
5
3
0
1
1
1
2
0
Alamo
1
0
0
0
0
0
0
0
0
Albany
3
4
2
2
4
2
2
0
1
Amager
0
0
0
0
2
0
0
0
1
Anatum
25
16
15
17
12
10
7
9
10
Anecho
0
0
0
0
0
0
0
0
0
Ank
0
1
0
0
0
0
0
0
0
Antartica
0
2
0
0
0
0
0
0
0
Antsalova
0
0
1
0
0
0
0
0
0
Arizonae
6
2
5
2
5
0
1
4
2
Augustenborg
0
0
0
0
0
0
0
0
0
Austin
0
0
0
0
0
0
0
1
0
Baildon
0
0
3
0
0
3
0
0
0
Bareilly
2
6
9
7
3
4
6
5
7
Bere
0
0
0
0
0
0
0
0
0
Berlin
1
0
0
0
0
0
0
0
0
Berta
17
15
108
11
6
7
9
25
41
Bilthoven
0
0
1
0
0
0
0
0
0
Binza
1
0
0
0
0
0
0
0
0
Bledgam
0
0
0
1
0
0
0
0
0
153
Table 13. Frequency of Salmonella serotypes in Illinois, 1993-2001
Serotype
1993
1994
1995
1996
1997
1998
1999
2000
2001
Blockley
5
8
1
3
6
3
4
5
1
Bonariensis
0
0
1
0
0
1
1
0
1
Bonn
0
0
1
0
0
1
0
0
0
Bovis-morb
2
4
2
6
4
11
5
7
3
Bradford
1
0
0
0
0
0
0
0
0
Braenderup
25
26
61
37
26
32
28
18
16
Brandenburg
18
18
12
18
14
10
5
5
9
Bredeney
3
4
2
4
6
3
0
0
2
California
1
0
0
0
0
0
0
0
0
Carmel
0
0
1
0
0
0
0
0
0
Carrau
0
0
2
0
0
0
0
0
0
Cerro
2
3
1
0
1
0
0
1
0
Chailey
2
0
0
0
3
2
0
2
0
Chameleon
1
0
0
1
1
0
1
1
0
Chandans
0
0
0
0
0
0
0
0
0
Chester
2
1
1
3
1
1
3
3
6
21
17
15
11
6
3
7
4
2
Coeln
0
0
0
0
0
0
0
0
0
Colindale
0
0
0
0
0
1
0
0
2
Cubana
5
6
6
3
4
2
0
1
2
Decatur
1
0
0
0
0
0
0
0
0
Denver
0
0
1
0
2
0
0
0
0
Derby
18
18
23
12
11
13
14
14
9
Drypool
1
0
0
0
0
0
0
0
0
Dublin
2
1
0
2
1
0
0
0
0
Duesseldorf
0
0
1
0
0
0
0
0
0
Cholerae-suis
154
Table 13. Frequency of Salmonella serotypes in Illinois, 1993-2001
Serotype
1993
1994
1995
1996
1997
1998
1999
2000
2001
Durban
1
0
0
1
0
0
0
0
0
Durham
0
0
0
0
0
1
0
0
1
Ealing
0
2
3
2
0
0
1
0
0
Eastbourne
0
1
2
1
0
1
1
1
0
Emek
0
0
0
1
0
0
1
0
0
647
413
397
484
519
405
264
262
246
Finkenwerden
0
0
0
0
0
0
1
0
0
Flint
2
0
0
1
1
1
2
0
1
Fluntern
0
1
0
0
0
0
0
0
0
Gallinarum
0
1
0
0
0
0
0
0
0
Gaminara
0
0
2
2
1
0
1
0
2
Gatuni
1
0
0
0
0
0
0
0
0
Give
4
1
3
7
7
5
4
1
1
Gloucester
0
0
0
1
0
0
0
0
0
Godesburg
0
0
0
1
0
0
0
0
0
Haardt
0
0
1
0
0
0
0
0
1
Hadar
43
42
52
37
75
40
15
26
8
Haifa
0
0
1
0
0
0
0
1
0
Hartford
5
12
22
6
4
12
16
18
15
Havana
6
0
0
6
1
1
2
2
1
159
109
164
117
121
115
101
101
66
Herston
0
0
0
1
0
0
0
0
0
Hull
0
0
0
0
0
0
0
1
0
Hvittingfoss
1
0
1
2
0
2
1
3
1
Idikan
1
0
0
1
0
0
0
0
0
Indiana
2
1
0
0
0
0
2
0
0
Enteritidis
Heidelberg
155
Table 13. Frequency of Salmonella serotypes in Illinois, 1993-2001
Serotype
1993
1994
1995
1996
1997
1998
1999
2000
2001
Infantis
29
27
33
34
42
65
51
38
35
Inpraw
0
0
0
0
0
0
0
0
0
Inverness
0
1
3
1
0
0
1
0
0
Irumu
3
3
1
0
0
0
0
0
0
Java
11
28
45
24
30
37
41
35
24
Javiana
18
15
8
23
20
11
27
24
17
Johannesburg
5
8
9
3
6
4
6
3
3
Kentucky
3
4
2
2
2
0
4
1
3
Kiambu
0
0
2
0
0
0
1
2
2
Kingabwa
0
0
0
0
0
0
0
0
1
Kintambo
1
3
0
0
0
0
1
0
1
Kottbus
0
0
0
1
0
0
0
0
2
Kua
0
0
1
0
0
0
0
0
1
Litchfield
6
4
13
6
4
7
10
9
9
Livingstone
2
1
0
0
0
0
0
0
1
Lome
1
0
0
0
1
0
0
0
0
Lomita
0
0
0
0
0
0
0
0
0
London
1
4
5
2
4
4
3
4
0
London
1
4
5
2
4
4
3
4
0
Manchester
0
0
0
1
0
0
0
0
0
Manhattan
20
12
12
18
35
15
4
8
4
Mmarina
4
4
5
6
1
3
2
3
3
Matadi
0
1
1
0
0
0
0
0
0
Mbandaka
9
1
9
23
10
2
10
7
7
Meleagridis
1
1
0
3
0
3
0
0
0
Memphis
0
0
0
0
1
0
0
0
0
156
Table 13. Frequency of Salmonella serotypes in Illinois, 1993-2001
Serotype
1993
1994
1995
1996
1997
1998
1999
2000
2001
Menhaden
0
0
1
0
0
0
0
0
0
Miami
6
8
5
2
5
3
4
2
4
Mikawasima
0
0
0
0
0
0
0
0
1
Minnesota
0
0
1
2
0
0
0
3
3
Mississippi
0
1
0
0
5
2
3
3
0
Mjordan
1
0
0
0
0
0
0
0
0
Monschaui
0
2
0
0
0
0
0
1
0
122
23
19
18
48
62
56
35
16
0
0
0
0
2
0
0
0
0
115
30
64
40
20
31
36
32
42
Muenster
4
1
5
1
4
10
1
3
2
Napoli
0
0
0
0
0
0
0
0
1
New-brunswick
1
0
1
0
1
0
1
1
0
Newington
0
2
1
0
1
2
3
0
0
49
84
95
56
40
71
59
85
121
Nima
0
0
0
0
0
1
0
1
2
Norwich
3
4
1
1
4
0
4
6
2
Offa
0
0
0
0
0
0
0
0
0
Ohio
5
5
9
4
3
7
3
0
6
Onderstepoort
0
0
0
0
0
1
0
0
0
22
42
25
38
24
26
21
24
28
Oslo
0
0
0
3
0
1
5
1
1
Overschie
1
0
0
0
0
0
0
0
0
Panama
8
9
17
9
10
3
3
2
9
Paratyphi a
3
10
11
10
4
11
1
11
2
Paratyphi b
0
0
6
11
5
1
1
1
0
Montevideo
Morotai
Muenchen
Newport
Oranienberg
157
Table 13. Frequency of Salmonella serotypes in Illinois, 1993-2001
Serotype
1993
1994
1995
1996
1997
1998
1999
2000
2001
Paratyphi c
0
0
0
0
0
0
0
0
1
Parera
0
0
0
0
0
0
0
0
0
Plymouth
0
0
0
1
0
0
0
0
0
Poano
0
1
0
0
0
0
1
0
0
Pomona
0
0
1
0
2
11
0
0
0
11
19
26
16
14
18
19
16
12
Portsmouth
0
0
0
0
1
0
0
0
0
Potsdam
0
1
0
0
0
0
0
0
0
Putten
0
0
0
1
0-
1
1
0
0
68
8
11
24
6
6
2
6
4
Richmond
0
0
0
1
1
0
0
0
0
Rissen
0
0
0
0
0
0
0
1
2
Romanby
1
0
0
0
1
0
0
0
0
Roodepoort
0
0
0
0
0
1
0
0
0
Roterberg
0
0
0
0
0
1
0
0
0
Rubislaw
1
0
2
1
1
2
0
1
1
San-diego
4
2
4
2
2
1
0
3
1
Saint-paul
35
26
20
24
22
30
21
28
22
Schwarzengrun
8
14
4
8
5
4
7
3
1
Senftenberg
6
12
10
18
11
8
13
9
12
Shubra
0
0
0
0
1
0
0
0
0
Simi
0
0
0
0
0
0
0
0
1
Singapore
0
0
0
1
0
0
0
2
0
Stanley
6
11
31
10
10
7
12
5
4
Stanleyville
0
0
1
0
0
0
1
0
0
Stendal
0
0
1
0
0
0
0
0
0
Poona
Reading
158
Table 13. Frequency of Salmonella serotypes in Illinois, 1993-2001
Serotype
1993
1994
1995
1996
1997
1998
1999
2000
2001
Sundsvall
0
1
0
1
1
1
0
0
0
Takoradi
0
0
1
0
0
0
0
0
1
Tallahasse
0
0
1
0
0
0
0
0
0
Telelkebir
3
0
0
1
2
0
1
2
0
Tennessee
5
9
8
4
1
3
2
0
2
Thomasville
0
0
0
0
0
0
0
0
0
35
34
35
27
24
34
30
36
24
1
0
0
0
0
0
0
0
0
347
384
364
404
417
405
354
350
285
Uganda
4
2
3
7
6
6
5
8
15
Urbana
1
4
2
3
3
5
7
2
2
Uzaramo
0
0
1
0
0
0
0
0
0
Virchow
4
2
3
9
4
1
8
2
4
Wandsworth
0
0
0
0
0
0
0
0
1
Wangata
0
0
0
0
0
0
0
2
1
Wassenaar
1
0
0
1
1
0
0
1
0
Weltevreden
1
1
0
3
1
5
3
0
2
Weston
0
0
0
0
0
0
0
0
0
Wien
0
0
0
0
0
0
0
0
0
Worthington
3
5
8
2
0
2
1
1
0
112
97
130
206
154
158
152
123
156
Thompson
Treguier
Typhimurium
Untyped
159
Sexually Transmitted Diseases
Included in this section are three diseases – chlamydia, gonorrhea and syphilis –
transmitted primarily or exclusively through sexual contact and reportable under Illinois statutes
and administrative rules. Other diseases not included in this section (such as herpes and human
papilloma virus) may be transmitted sexually. HIV/AIDS is discussed in a separate section.
The control of sexually transmitted diseases (STDs) is an important strategy for the
prevention of HIV. The inflammation and lesions associated with STDs increase an individual’s
risk for acquisition of HIV, as well as the ability to transmit HIV to others.
Chlamydia
Background
Chlamydia trachomatis infection is a significant cause of genitourinary complications,
especially in women. Early symptoms of cervicitis or urethritis are mild; asymptomatic infection
is common in both women and men. If left untreated, chlamydia infection can lead to pelvic
inflammatory disease in women. It may cause severe fallopian tube inflammation and damage,
even though symptoms may be mild. Due to the insidious nature of the infection, C. trachomatis
is a major cause of long-term sequelae such as tubal infertility and ectopic pregnancy. Chlamydia
also can cause ophthalmia and pneumonia in newborns exposed to it during birth.
Chlamydia is reportable in all but one state. During 2001, 783,242 chlamydia infections
were reported to the CDC, making chlamydia the most commonly reported notifiable disease in
the United States. However, national data are incomplete because the majority of testing is
currently conducted in females.
Federal and state funding for chlamydia is targeted at providing screening programs in
STD clinics, women’s health programs (such as family planning and prenatal clinics), and in
adult and juvenile correctional centers.
Case definition
The case definition is isolation of C. trachomatis by culture, or demonstration of C.
trachomatis in a clinical specimen by detection of antigen or nucleic acid.
Descriptive epidemiology
Note: The numbers of reported chlamydia cases from 1996 through 2000 were revised as
additional cases came in (compared to the 2000 annual report of infectious diseases).
•
Number of cases reported in Illinois in 2001 – 43,716; the overall incidence rate was 352
per 100,000 population. The number of cases increased by 89 percent from 1991 (23,099)
to 2001 (43,716) (Figure 81).
•
Age – Adolescents (ages 15 to 19) accounted for 35 percent of reported chlamydia cases
(1,692 per 100,000) in 2001 (Figure 82). The average age of persons reported with
chlamydia was 23.
•
Gender – Most reported cases were in women (76 percent) due to screening efforts that
target this group. The female-to-male ratio of reported cases was 3.1: 1.
160
•
•
•
Race/ethnicity – Incidence rates per 100,000 population by racial/ethnic group were
African American, 1219; white, 109; and Native American or Asian or Pacific Islander,
61.
Geographic distribution – Chlamydia is geographically distributed throughout the state.
Cases were reported from 100 of 102 counties. The five counties with the highest
incidence rates per 100,000 were Alexander (845), St. Clair (618), Pulaski (517) and
Macon (517) and Cook (516).
IDPH laboratories conducted more than 200,000 chlamydia tests during 2001 with a
positivity rate of 7.5 percent.
Summary
Chlamydia is the most commonly reported sexually transmitted disease in Illinois. Cases
were reported from all but two Illinois counties during 2001. Adolescents had the highest
incidence rates. Reasons for the rising number of cases between 1991 and 2001 include increased
testing, improved surveillance and the use of more sensitive diagnostic tests.
161
Gonorrhea
Background
Gonorrhea is a bacterial infection caused by Neisseria gonorrhoeae. Uncomplicated
urogenital infection may progress, without treatment, to complications such as infertility, pelvic
inflammatory disease (PID) and disseminated infection. Resultant scarring of fallopian tubes may
result in ectopic pregnancy. Women are more likely than men to suffer complications from
gonorrhea infection because early symptoms are often not present or not recognized in females.
Infants born to infected mothers may develop gonococcal ophthalmia, which is potentially
blinding, or sepsis, arthritis or meningitis. The United States recorded 361,705 cases of
gonorrhea in 2001.
Currently recommended therapies for gonorrhea are highly effective, although
antimicrobial drug resistance has been a problem. Gonococcal susceptibility to some currently
recommended drugs is gradually declining, and active surveillance is required to monitor
resistance and to ensure the effectiveness of therapy.
Case definition
Isolation of typical gram-negative, oxidase positive diplococci (presumptive Neisseria
gonorrhoeae) from a clinical specimen; demonstration of N. gonorrhoeae in a clinical specimen
by detection of antigen or nucleic acid; or observation of gram-negative intracellular diplococci
in a urethral smear obtained from a male or female endocervical smear.
Descriptive epidemiology
Note: Gonorrhea numbers reported from 1996 through 2000 were adjusted with new reported
cases compared to the 2000 annual report.
•
Number of cases reported in Illinois in 2001 – 24,025; case rate was 193 per 100,000
population. Reported cases in 2001 were similar to the number reported in 2000 (Figure
83). Gonorrhea is the second most commonly reported STD in Illinois.
•
Age – Adolescents and young adults are at greatest risk for gonorrhea infection. Persons
ages 15 to 24 accounted for 61 percent of reported cases in 2001 and adolescents (ages 15
to 19) for 27 percent (Figure 84). [The case rate among adolescents is much higher than
among the general population: 714 cases per 100,000 vs. 193]. The average age of
gonorrhea cases in 2001 was 27 for males and 23 for females.
•
Race/ethnicity – Illinois minorities are disproportionately affected by gonorrhea. The case
rate among African Americans was 874 per 100,000 population, compared to an overall
state rate of 193. The rates per 100,000 for other racial groups were Native American, 52,
and Asian/Pacific Islanders, 34; the rate for Hispanics was 34.
•
Geographic distribution – At least one case of gonorrhea was reported in each of 88
Illinois counties. The five counties with the highest incidence rate in 2001 were
Alexander (688), Macon (435), St. Clair (351), Kankakee (332) and Peoria (316).
•
IDPH laboratories processed more than 200,000 gonorrhea tests with a positivity rate of
4.5 percent. The highest positivity rate was in specimens received from STD clinics (11
percent).
162
Summary
Gonorrhea is the second most commonly reported sexually transmitted disease after
chlamydia in Illinois. In 2001, 27 percent of the state’s cases were in those 15-19 years of age.
163
Syphilis
Background
Syphilis is a systemic disease caused by the spirochete Treponema pallidum. The
infection is definitively diagnosed through microscopic examination of lesion exudates and
presumptively through serologic testing. Without treatment, syphilis infection progresses through
four stages: primary, characterized by a painless ulcer at the point at which the organism entered
the body (genitals, mouth, anus); secondary, characterized by lesions, rashes, hair loss,
lymphadenopathy and/or flu-like symptoms; latent with no signs or symptoms; and late
symptomatic, in the form of neurosyphilis (with neurologic damage) and tertiary (cardiovascular
or gummatous) disease.
The open lesions of syphilis are infectious to sex partners. Syphilis during pregnancy can
lead to a congenital form of the disease that may result in stillbirth or severe illness and lifelong
debilitating consequences for the infant. Increases in syphilis often are associated with poverty,
limited availability of health services and the exchange of sex for drugs or money. Syphilis
outbreaks are often a precursor of HIV increases in affected populations because the lesions
caused by syphilis increase the likelihood of both acquisition and transmission of HIV.
Public health disease intervention efforts emphasize control of early syphilis because
persons with this stage of the disease are most likely to have been infectious within the past year.
Many individuals do not notice or recognize the symptoms of syphilis, so screening for latent
disease and partner notification and referral are important components of control efforts.
The CDC recorded 6,103 primary and secondary syphilis cases in the United States in
2001. The rate of infection was 2.2 per 100,000 population.
Case definition
Syphilis is a complex disease with a highly variable clinical course. The following case
definitions are used for surveillance purposes for syphilis that has not progressed to late
symptomatic stages.
•
Primary. A clinically compatible case with one or more ulcers (chancres) consistent with
primary syphilis and a reactive serologic test; or demonstration of T. pallidum in clinical
specimens by dark field microscopy, fluorescent antibody or equivalent methods.
•
Secondary. A clinically compatible case with a reactive nontreponemal test titer of > 1:4
(probable case), or demonstration of T. pallidum in clinical specimens by dark field
microscopy, fluorescent antibody or equivalent methods (confirmed case).
•
Latent. No clinical signs or symptoms of syphilis and the presence of one of the
following:
<
No past diagnosis of syphilis, a reactive nontreponemal test and a reactive
treponemal test, or
<
A past history of syphilis therapy and a current nontreponemal test titer
demonstrating fourfold or greater increase from the last nontreponemal test titer.
164
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 45 congenital cases and 409 primary or
secondary cases (Figure 85), down 1 percent from 2000. Incidence rate was three per
100,000 population for primary and secondary syphilis and 24 per 100,000 live births for
congenital syphilis.
•
Age – The average age of persons diagnosed with primary and secondary syphilis was 34.
Persons 20- to-39 years-old accounted for 69 percent of cases (Figure 86).
•
Gender –77 percent of cases were male.
•
Race/ethnicity – Minorities in Illinois are disproportionately affected by syphilis,
especially African Americans, who accounted for 84 percent of the congenital syphilis
cases. The 2001 incidence rates for primary and secondary cases per 100,000 by race
were African Americans, 11; whites, 1.5; Native Americans, 0; and Asian/Pacific
Islanders, 0. The rate for Hispanics was 2.
•
Geographic distribution – Syphilis is more prevalent in urban populations. The disease
has become progressively concentrated geographically. Cases were reported from 16
counties. Only four Illinois counties reported five or more cases in 2001. Cook County
ranked first (339 cases) in reported cases among Illinois counties.
•
Clinical Presentation - 23 neurosyphilis cases were reported.
Summary
Primary and secondary syphilis cases declined by 1 percent in 2001 compared to 2000.
Minority racial/ethnic populations are disproportionately affected by syphilis in Illinois.
165
166
Shigellosis
Background
Shigellosis is an acute bacterial disease of humans and non-human primates caused by
four species or serogroups of Shigella: S. dysenteriae (group A), S. flexneri (group B), S. boydii
(group C) and S. sonnei (group D). The infectious dose is low; as few as 10 to 100 bacteria can
cause infection. Transmission is via direct or indirect fecal-oral routes. Shigella can be sexually
transmitted through indirect or direct oral-anal contact. S. sonnei can cause large community
outbreaks in men who have sex with men. Cases with shigellosis should abstain from sexual
behavior that is likely to transmit infection for at least three days after starting antibiotics. The
incubation period is usually one to three days. Symptoms of the disease are watery or bloody
diarrhea with fever and sometimes vomiting or tenesmus. Mild and asymptomatic infections can
occur. Duration of illness is usually from four to seven days. Disease caused by Shigella
dysenteriae type 1 is the most severe form (case fatality rate=20 percent) and can cause
hemolytic uremic syndrome (HUS) due to a toxin similar to that produced by E. coli O157:H7.
Antimotility drugs are contraindicated. Antimicrobial therapy can limit the clinical course and
duration of fecal excretion of Shigella.
Of the 10 diseases/syndrome (those caused by Campylobacter, Cryptosporidium,
Cyclospora, HUS, E. coli O157:H7, Listeria monocytogenes, Salmonella, Shigella, Vibrio and
Yersinia enterocolitica) under active surveillance in the federal FoodNet sites, Shigella
comprised 16 percent of the reported infections in 2001 data. The incidence rate per 100,000 for
Shigella ranged from one to 13 at the nine FoodNet sites. In Illinois in 2001, there were no
outbreaks of Shigella associated with foodborne transmission.
In 2001, 20,221 cases were reported to CDC. S. sonnei accounts for three-quarters of
shigellosis cases in the United States. S. sonnei infections are increasing in men who have sex
with men.
Case definition
The case definition for a confirmed case of shigellosis in Illinois is a case from which
Shigella is isolated from a clinical specimen. The case definition for a probable case is a person
who has a clinically compatible illness that is epidemiologically linked to a confirmed case, but
is not laboratory confirmed.
Descriptive epidemiology
•
Number of reported cases in Illinois in 2001 – 630 (five-year median = 1,188) (Figure
87). Overall annual incidence rate was five per 100,000.
•
Age – Median age = 12 (Figure 88). By age group, annual incidence rates per 100,000
were 1 – 4 years of age, 23; 5 – 9 years of age, 13; younger than 1-year-old, 6; 10 – 19
years of age, 2; 20 – 29 years of age, 5; 30 – 59 years of age, 3; and 60 and older, 1.
•
Gender – 49 percent were female.
•
Race/ethnicity – 75 percent were white, 21 percent were African American and 4 percent
were other races; 26 percent were Hispanic. There were significantly higher proportions
of African Americans and Hispanics with shigellosis compared to their representations in
167
•
•
•
the Illinois population.
Geographic distribution – One-year incidence rates by county for 1997 to 2001 ranged
from 0 to 31 per 100,000 population. The five highest annual incidence rates per 100,000
for this time period were in Champaign (31), Whiteside (29), Crawford (26), Peoria (26)
and Rock Island (24) counties. County incidence for the state is shown in Figure 89.
Seasonal variation – Shigellosis cases occurred in all months of the year with a peak in
the months of July through October (Figure 90).
Serotypes – 88 percent of isolates were serotyped in 2001. The most common species was
S. sonnei (83 percent), followed by S. flexneri (16 percent). S. boydii made up 1 percent
of typed isolates. The most common S. boydii serotype was 2 (Table 14). No S.
dysenteriae cases were reported (Table 15). The two most common S. flexneri serotypes
were 2 (23 cases) and 3 (14 cases) (Table 16). S. sonnei does not have differing subtypes.
Summary
There were less than 1,000 reported cases of shigellosis in Illinois in 2001. The incidence
rate was five per 100,000, which is within the range reported at CDC’s FoodNet sites. There was
a decline in incidence of shigellosis compared to 2000. The decline occurred in all age groups
except those 60 years and older whose incidence rates were low and steady. The proportion who
were Hispanic or African American was higher than the representation of each group in the
Illinois population. The median age of cases was 12 years. S. sonnei was the most common
species found in Illinois, which is the same as the most common species identified in CDC’s
FoodNet sites. Isolates of Shigella are required to be submitted to IDPH laboratories for
speciation and/or serotyping (if this cannot be done by the clinical laboratory). This can help in
outbreak identification.
Suggested readings
MMWR. Summary of notifiable diseases-United States, 2001. MMWR 2003;
50(53):p.xx.
MMWR. Shigella sonnei outbreak among men who have sex with men-San Francisco,
California, 2000-2001. MMWR 2001; 50(42):922-26.
168
Figure 89. One-year shigellosis incidence rates by county, Illinois, 1997-2001
Source: Illinois Department of Public Health, 2002
169
Table 14. Frequency of Shigella boydii subtypes in Illinois, 1993-2001
Type
1993
1994
1995
1996
1997
1998
1999
2000
2001
boydii, unknown
0
0
0
0
0
0
0
0
0
boydii 1
4
1
2
2
1
5
0
0
2
boydii 2
17
6
9
6
9
11
4
4
3
boydii 3
0
0
1
0
0
0
0
0
0
boydii 4
2
3
3
6
4
2
7
2
0
boydii 5
1
0
0
0
0
0
0
1
0
boydii 10
0
0
1
1
1
1
1
0
0
boydii 11
0
0
0
0
0
1
0
1
0
boydii 12
1
0
1
0
0
0
1
0
0
boydii 13
0
0
0
0
0
0
0
1
0
boydii 14
1
1
1
1
2
2
2
2
1
boydii 18
0
0
0
0
0
0
4
1
0
boydii 19
0
0
1
0
0
0
0
0
0
26
11
19
16
17
21
19
12
6
TOTAL boydii
Source: Illinois Department of Public Health, 2002
170
Table 15. Frequency of Shigella dysenteriae subtypes in Illinois, 1993-2001
Type
1993
1994
1995
1996
1997
1998
1999
2000
2001
dysenteriae, unknown
0
1
0
1
1
0
0
2
0
dysenteriae 1
0
1
0
0
0
0
1
0
0
dysenteriae 2
2
1
3
0
0
4
4
0
0
dysenteriae 3
0
1
6
3
0
4
0
0
0
dysenteriae 4
0
0
0
2
0
0
0
0
0
dysenteriae 9
0
0
1
0
0
0
0
0
0
dysenteriae 12
0
0
1
0
0
0
0
0
0
TOTAL dysenteriae
2
4
11
6
1
8
5
2
0
Source: Illinois Department of Public Health, 2002
171
Table 16. Frequency of Shigella flexneri subtypes in Illinois, 1993-2001
Type
1993
1994
1995
1996
1997
1998
1999
flexneri, unknown
17
31
63
59
36
36
39
flexneri 1
67
44
22
31
18
9
11
3
5
flexneri 1A
0
0
0
0
0
0
0
0
0
flexneri 1B
1
0
0
0
0
0
1
0
0
70
47
44
35
44
53
64
49
23
flexneri 2A
1
0
0
0
3
0
1
0
0
flexneri 2B
1
0
0
0
0
0
0
0
0
34
19
42
21
20
40
24
27
14
flexneri 3A
0
0
0
0
0
0
0
0
0
flexneri 3B
1
0
1
0
0
0
0
0
0
22
16
25
16
19
14
15
10
11
flexneri 4A
0
2
5
8
3
1
0
1
0
flexneri 4B
0
0
0
0
0
0
0
0
0
flexneri 5
4
3
1
0
0
0
0
0
0
flexneri 5A
0
0
0
1
0
0
0
0
0
11
38
25
15
6
15
11
8
9
0
0
0
0
0
0
0
1
3
229
200
228
186
149
168
166
130
89
flexneri 2
flexneri 3
flexneri 4
flexneri 6
flexneri Y variant
TOTAL flexneri
Source: Illinois Department of Public Health, 2002
172
2000
31
2001
24
Staphylococcus aureus, intermediate or high-level vancomycin resistance
Background
Staphylococcus aureus causes both community and health care associated infections in
persons. The National Committee for Clinical Laboratory Standards defines staphylococci
requiring concentrations of vancomycin of < 4 ug/mL for growth inhibition as susceptible to
vancomycin; those requiring concentrations of 8-16 ug/mL as intermediate; and those requiring
concentrations of > 32 ug/mL as resistant. S. aureus with reduced vancomycin susceptibility
(SA-RVS) includes all S. aureus isolates with minimum inhibitory concentration (MIC) of
vancomycin of > 4 ug/mL.
A study by CDC of U.S. cases from 1997-2001 found that risk factors for infection were
antecedent vancomycin use and prior oxacillin-resistant S. aureus infection two or three months
before the current infection.
Three cases of SA-RVS have been identified in Illinois, two in 1999 and one in 2000.
The first Illinois case occurred in March 1999. The organism was isolated from blood with a
MIC of 4 ug/mL taken from a 67-year-old. The patient had vertebral osteomyelitis secondary to
recurrent methicillin resistant S. aureus (MRSA) cellulitis and bacteremia and diabetes mellitus.
The patient had been exposed to 14 weeks of vancomycin. The infection cleared but the patient
died of multi-organ failure. The S. aureus was isolated in April 1999 from blood with a MIC of
8 ug/mL taken from a 63-year-old patient. The patient had mitral valve endocarditis, was on
long-term hemodialysis and had recurrent catheter-associated MRSA bacteria. The patient had
been on four weeks of vancomycin. The second Illinois case was fatal. The third isolate was
obtained from a wound in March 2000 from a 67-year-old; it showed a MIC of 4 ug/mL. The
patient had a skin ulcer, recurrent MRSA wound infection, foot amputation, diabetes mellitus
and vascular disease. The third patient had been on nine weeks of vancomycin therapy and the
infection was cleared.
Case definition
A case of S. aureus with, intermediate or high-level vancomycin resistance is defined as
S. aureus isolated from infected humans with an MIC of vancomycin of > 4 ug/mL.
Descriptive epidemiology
No cases were reported in 2001.
Summary
No cases were reported in 2001 in Illinois.
Suggested readings
Fridkin SK et al. Epidemiologic and microbiological characterization of infections
caused by Staphylococcus aureus with reduced susceptibility to vancomycin, United States,
1997-2001. CID 2003;36:429-39.
173
Streptococcus pyogenes, group A (invasive disease)
Background
The spectrum of disease caused by group A streptococci (GAS) is diverse and includes
pharyngitis and pyoderma, severe invasive infections, post-streptococcal acute rheumatic fever
and acute glomerulonephritis. Invasive GAS may present as any of several clinical syndromes
including pneumonia, bacteremia in association with cutaneous infection (cellulitis, erysipelas or
infection of a surgical or nonsurgical wound), deep soft tissue infection (myositis or necrotizing
fasciitis), meningitis, peritonitis, osteomyelitis, septic arthritis, postpartum sepsis (puerperal
fever), neonatal sepsis and non-focal bacteremia. Two types of invasive GAS are streptococcal
toxic shock syndrome (STSS) and necrotizing fasciitis. The symptoms of STSS include fever,
myalgia, vomiting, diarrhea, confusion, soft tissue swelling, renal dysfunction, respiratory
distress and shock. Necrotizing fasciitis is a deep infection of subcutaneous tissue that results in
destruction of fat and fascia and often leads to systemic illness. Risk factors for necrotizing
fasciitis include injection drug use, obesity and diabetes mellitus. In a California study, more than
half of all necrotizing fasciitis cases were in injection drug users. One-third of non-injection drug
user cases reported a history of recent spider or insect bite at the site of infection. Clusters of
GAS have occurred in health care workers from exposure to a patient with invasive GAS.
Transmission of GAS occurs by direct contact with patients or carriers, or by inhalation
of large respiratory droplets. Approximately 5 percent of the population may be asymptomatic
carriers, but these individuals are less likely to transmit the organism than symptomatic persons.
Predisposing risk factors for invasive GAS include older age, injection drug use, human
immunodeficiency infection, diabetes, cancer, alcohol abuse, varicella, penetrating injuries,
surgical procedures, childbirth, blunt trauma and muscle strain. Treatment guidelines have been
established by the Infectious Diseases Society for GAS pharyngitis. No chemoprophylaxis is
recommended for all household contacts to cases of invasive GAS. Household members should
monitor themselves for signs and symptoms for 30 days after exposure. Health care providers
may chose to offer chemoprophylaxis to household contacts if they are over 64 years of age or
are at increased risk for sporadic invasive GAS infection (HIV infection, diabetes mellitus,
chickenpox infection, cancer, heart disease, injection drug use, steroid use, Native Americans).
In five states with active surveillance from 1995 through 1999, the most common emm
types were 1, 28, 12, 3 and 11. Predictors of death from invasive GAS were older age, presence
of streptococcal toxic shock syndrome, meningitis or pneumonia; and infection with emm 1 and
emm 3. The overall case fatality for invasive GAS disease was 12.5 percent.
During 2001, 1,147 cases of invasive GAS were reported from the Active Bacterial Core
Surveillance site projects in nine states. Incidence was highest in children younger than 1 year of
age (five per 100,000) and adults greater than 65 years (10 per 100,000). STSS accounted for 6
percent and necrotizing fasciitis accounted for 7 percent of cases.
Case definition
The case definition of invasive GAS disease in Illinois is the isolation of group A
Streptococcus pyogenes by culture from a normally sterile site.
174
Descriptive epidemiology
•
Number of reported cases in Illinois in 2001 – 272 (five-year median = 193) ( Figure 91).
Average annual incidence for the one-year period was 2.2 per 100,000 population.
•
Age – Median age was 55 (Figure 92). By age group, the highest incidence per 100,000
occurred in those older than 79 years of age (10), followed by those 70 to 79 years of age
(6) and 60 to 69 years of age (4). At least 10 cases were residents of long-term care
facilities.
•
Gender – 53 percent were female.
•
Race/ethnicity – Cases were 81 percent white, 17 percent African American and 1 percent
other races; 8 percent were Hispanics.
•
Geographic distribution – About 47 percent were residents of Cook County.
•
Seasonal variation – Cases were more likely during the winter months (Figure 93).
•
Positive cultures – Cultures were positive from blood (84 percent), synovial fluid (4
percent), tissue (8 percent), pleural fluid (2 percent), pericardial fluid (3 percent),
cerebrospinal fluid (2 percent) and other sources (3 percent). Individual cases may have
had positive cultures from more than one site.
•
Diagnosis – 10 of the invasive GAS cases were described as necrotizing fasciitis and 17
were described as toxic shock syndrome. Signs and symptoms reported by cases included
hypotension (32 percent), renal impairment (27 percent), rash (18 percent), acute
respiratory distress syndrome (8 percent) and sore throat (7 percent).
•
Clinical syndromes – Where type of infection was indicated, the following conditions
were reported: sepsis (41 percent), cellulitis (37 percent), pneumonia (21 percent),
nonsurgical wound (14 percent), septic arthritis (7 percent), osteomyelitis (2 percent),
disseminated intravascular coagulation (5 percent), postpartum (4 percent), meningitis (3
percent) and peritonitis (3 percent). Cases may have reported more than one type of
infection.
•
Underlying disease – Reported in 68 percent of cases; conditions were diabetes (23
percent), heart conditions (30 percent), malignancy (20 percent), non-surgical wounds (14
percent), immunosuppressive therapy (13 percent), chronic lung disease (12 percent),
blunt trauma (12 percent), surgical wound (7 percent), stroke (6 percent), renal dialysis (6
percent), vascular problems (5 percent), alcohol abuse (4 percent), intravenous drug use
(4 percent) and liver cirrhosis (2 percent). Three cases reported prior varicella infections.
•
Treatment – 91 percent of cases were hospitalized. Procedures needed on cases included
debridement (9 percent) and amputation (2 percent). Cases where amputation was needed
were all diabetic cases.
•
Mortality – Of 212 reported invasive GAS infections with investigation forms available,
33 were fatal (overall case fatality rate of 16 percent). More than 82 percent of the
fatalities were in those older than 49 years of age.
•
Clusters – A cluster of two cases of invasive GAS occurred in a long-term care facility in
Will County in April 2001. A 92-year-old resident had a positive blood culture for GAS
and an 88-year-old resident had a positive blood culture. Approximately 240 residents
and direct care staff were cultured. Five residents and one employee were culture positive
and were treated.
Summary
175
The number of reported invasive GAS cases was 272 in 2001, an increase from 2000 and
higher than the previous five-year median. Almost half of the cases were older than 60 years of
age. Eighty-two percent of the fatalities were in cases older than 49 years of age.
Suggested readings
Bisno AL, Gerber MA et al. Practice guidelines for the diagnosis and management of
group A streptococcal pharyngitis. CID 2002;25:113-25.
Chen JL, Fullerton KE, Flynn NM. Necrotizing fasciitis associated with injection drug
use. CID 2001;33:6-15.
Kakis A et al. An outbreak of Group A streptococcal infection among health case
workers. CID 2002;35:1353-9.
O’Brien KL, Beall B et al. Epidemiology of invasive Group A streptococcus disease in
the United States, 1995-1999. CID 2002;35:268-76.
Prevention of Invasive GAS Infections Workshop participants. Prevention of invasive
Group A streptococcal disease among household contacts of case patients and among postpartum
and postsurgical patients: Recommendations from the Centers for Disease Control and
Prevention. CID 2002:35:950-9.
176
177
Tetanus
Background
Tetanus is induced by a toxin produced by Clostridium tetani, which grows anaerobically
at the site of a skin wound. The disease is characterized by muscular contractions. The reservoir
for the organism is the soil or fomites contaminated with human or animal feces. Tetanus spores
are common in the environment. The incubation period is three to 21 days. Prevention is through
immunization.
In 2001, 37 cases of tetanus were reported to CDC from 15 states. Eleven percent were in
persons less than 25 years of age, 51 percent in those aged 25-59 years of age and 28 percent in
those greater than 59 years of age. Seventeen percent of cases were fatal.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 2
•
Gender – Both reported cases were female.
•
Geographic distribution – Peoria and Logan counties.
•
Course of disease for Case 1– Case was walking on a park trail, slipped and punctured her
hand on a thorn. Almost three weeks later, she developed symptoms of localized tetanus
and received an initial treatment of tetanus immune globulin at a physician’s office,
followed by a second dose six days later. Immunization status is unknown except for
tetanus toxoid two days after injury. Patient survived.
•
Course of disease for Case 2– The case developed pruritis and scratched an opening on
her toe. About three months later, she began having neurologic problems including
trismus. She was treated with tetanus immune globulin and was hospitalized for
approximately three weeks. History of tetanus immunization 25 years ago. Patient
survived.
•
Immunization status – No history of tetanus immunization.
Summary
Two cases of tetanus were reported in 2001 in Illinois. Both patients survived.
Suggested readings
MMWR. Summary of notifiable disease-MMWR. Untied States 2001. MMWR
2003;50(53):p.xxiii.
178
Tick-borne diseases found in Illinois
At least 869 species of ticks have been identified in the world. Ticks are the most
common type of vectors for vectorborne diseases in the United States. Ticks are responsible for
carrying a number of diseases: babesiosis, Colorado tick fever, human granulocytic ehrlichiosis,
human monocytic ehrlichiosis, Lyme disease, Powassan encephalitis, relapsing fever, Rocky
Mountain spotted fever, tick paralysis, tularemia and, possibly, southern tick associated rash
illness.
In humans, ticks usually attach around the head and neck and in the groin area. The rates
of human infection with tick-borne diseases are influenced by the prevalence of vector ticks, the
tick infection rate, the readiness of ticks to feed on humans and the prevalence of their usual
animal hosts.
Six tick-borne diseases have been reported in Illinois residents. According to CDC
guidelines, any Illinois resident diagnosed with a tick-borne disease is counted in the state’s case
count, even though he/she may have reported tick exposures in another state. These tick-borne
diseases are listed in Table 17 and in individual sections of this document. Cases by year from
1996 through 2001 are shown in Figure 94.
Reports of tick-borne diseases overall were elevated in 2001 over previous years. For
ehrlichiosis, this may be due to increased reporting (reporting became mandatory on April 1,
2001). Tularemia reporting may have risen because of its categorization as a possible agent of
bioterrorism. The number of Rocky Mountain spotted fever cases also increased in 2001 over the
previous year. Lyme disease cases decreased slightly.
Suggested readings
Zaidi SA, Singer C. Gastrointestinal and hepatic manifestations of tickborne diseases in
the United States. CID 2002;34:1206-12.
179
Table 17. Tick-borne diseases reported in Illinois residents
Disease
Organism
Tick vectors
Symptoms
Where found
Human granulocytic
ehrlichiosis
Anaplasma
phagocytophilum
I. scapularis
fever, headache,
myalgia, vomiting
most common in
upper Midwest and
northeastern states;
in Illinois,
distribution
unknown
Human monocytic
ehrlichiosis
E. chaffeensis
A. americanum
(Lone star tick)
fever, headache,
myalgia, vomiting
most common in the
southern states;
most common in
southern Illinois
Lyme disease
B. burgdorferi
I. scapularis (deer
tick)
fatigue, chills,
fever, erythema
migrans, enlarged
lymph nodes
primarily on the
West Coast and in
northeastern and
north central U.S.;
primarily northern
Illinois
Rocky Mountain
spotted fever
Rickettsia rickettsii
D. variabilis
(American dog
tick), D. andersoni
(Rocky Mountain
wood tick)
fever, headache,
rash
thoughout the U.S.
but most common
in southeast;
throughout Illinois
Southern-tick
associated rash
illness (STARI)*
Borrelia lonestari
by DNA analysis,
not yet cultured
A. americanum
not well defined
not established yet;
in Illinois, southern
and west central
Ilinois
Tularemia
Francisella
tularensis
A. americanum, D.
variabilis, D.
andersoni
ulcer at entry site,
enlarged lymph
node
throughout North
America; primarily
central and southern
Illinois
* Although suspected to be present in Illinois, no diagnostic test is available yet.
Source: Illinois Department of Public Health, 2002
180
Toxic shock syndrome (TSS) due to Staphylococcus aureus
Background
Staphylococcal toxic shock syndrome (TSS) is characterized by sudden high fever,
vomiting, profuse watery diarrhea, myalgia and hypotension. A rash, which may result in
desquamation of the skin, occurs in the first two weeks of illness. Occasionally, shock occurs.
Three or more systems (gastrointestinal, muscular, mucous membranes, renal, hepatic,
hematologic or central nervous) are usually involved. Most cases have been associated with
strains of Staphylococcus aureus that produce a special toxin.
Case definition
The six clinical findings used to establish whether a case meets the case definition for
staphylococcal TSS are –
1)
Fever-temperature greater than 102" F
2)
Rash
3)
Desquamation
4)
Hypotension
5)
Multisystem involvement (three or more of the following)
a.
Gastrointestinal – vomiting or diarrhea
b.
Muscular – myalgia or creatine phosphokinase (>twice upper limit of normal)
c.
Mucous membrane – vaginal, oropharyngeal or conjunctival hyperemia
d.
Renal – blood urea nitrogen or creatinine at least twice the upper limit of normal
or urinary sediment with pyuria in the absence of urinary tract infection
e.
Hepatic – total bilirubin, serum glutamic-oxaloacetic transaminase (SGOT), or
serum glutamic-pyruvic transaminase (SGPT) at least twice the upper limit of
normal for the lab
f.
Hematologic – platelets less than 100,000/mm3
g.
CNS – disorientation or alterations in consciousness without focal neurologic
signs when fever and hypotension are absent
6)
Negative results on the following tests (if done)
a.
Blood, throat or CSF cultures (blood cultures can be positive for S. aureus)
b.
Rise in titer to Rocky Mountain spotted fever, leptospirosis or measles
The CDC case definition for a probable case is one with five of six of the above clinical
findings. A confirmed case is one with all six of the clinical findings, including desquamation,
unless the patient dies before desquamation can occur.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 4 (five-year median = 7) (Figure 95). Three
were confirmed and one was probable.
•
Age – Ages ranged from 14 to 36 years.
•
Gender – Three cases were female.
•
Race/ethnicity – All four cases were white; one case was Hispanic.
•
Geographic distribution – Cases resided in Brown, DuPage, Hamilton and Kane counties.
•
Symptoms – Rash (4 cases), fever (4 cases), hypotension (4 cases), desquamation (1
181
•
•
•
cases/1 unknown), myalgia (3 cases/1 unknown), vomiting (4 cases), vaginal discharge (1
case of 3 females/1 unknown), sore throat (4 cases) orthostatic dizziness (0 cases/3
unknown), disorientation (4 cases), oropharyngeal hyperemia (2 cases/2 unknown),
conjunctival hyperemia (3 cases/1 unknown), vaginal hyperemia (0 case of 3 females/3
unknown), abdominal pain (2 cases/1 unknown), injected tongue (2 cases/2 unknown)
and syncope (0 cases/3 unknown).
Laboratory findings – Staphylococcus aureus was isolated from breast tissue postoperatively (1 case), blood (1 case), urine and vagina (1 case) and vagina (1 case). Two
cases were classified as menstruation-associated.
Treatment – Three patients were hospitalized and the hospitalization history of the fourth
case was unknown.
Outcome – One case was fatal.
Summary
Among four cases of staphylococcal toxic shock reported in 2001, one case was fatal.
182
Trichinosis
Background
Trichinosis is caused by a nematode, Trichinella spiralis. People become infected by
consuming undercooked meat containing the cysts of the organism. Initial symptoms of disease
include diarrhea, vomiting and nausea that occur within a few days of ingestion. Gastrointestinal
symptoms may be absent. In the second phase of illness, which begins one to two weeks after
exposure, myalgias, periorbital edema, fever, cough, and cardiac and neurologic complications
may occur. Titers to trichinosis rise during the third to sixth week following infection.
Eosinophilia is common. Muscle biopsies demonstrating the non-calcified larvae of T. spiralis
indicate recent infection. Larvae also may be identified in suspect food. Swine in the United
States rarely have Trichinella. The estimated prevalence of Trichinella infection in U.S. swine
was estimated at 0.013 percent in 1995. Consumption of wild game, however, has become a
more common source of this infection in United States residents between 1997 and 2001. During
this five-year period, 72 cases were reported in the United States (median of 12 annually) and 43
percent were linked to wild game consumption, especially bear meat. Only 17 percent of cases
were linked to commercial pork production. The median incubation period was 13 days.
USDA recommends that fresh pork be cooked to an internal temperature of 160 F.
Freezing also helps kill T. spiralis. However, wild game Trichinella types can be found in frozen
meat.
Case definition
A confirmed case is defined as a clinically compatible case with either a positive
serologic test for Trichinella or demonstration of Trichinella larvae in tissue obtained by muscle
biopsy.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 1
•
Age – The case was 42 years of age.
•
Gender – The case was male.
•
Risk factor – The risk factor(s) for this case were unknown.
•
Symptoms – Case experienced fever, cough, stiff neck, rash, periorbital edema and
muscle pain.
•
Diagnosis – The case was serologically positive.
•
Outcome – This case recovered.
Summary
Only one case of trichinosis was reported in Illinois for 2001 and no potential source for
his illness could be identified.
Suggested Readings
MMWR. Trichinellosis surveillance-United States, 1997-2001. MMWR 2003;52(SS6):1-8.
183
Tuberculosis
Background
The Mycobacterium tuberculosis complex includes M. tuberculosis, M. africanum, M.
bovis and M. microti. Tubercle bacilli are transmitted by inhalation of airborne droplet nuclei
produced by persons with tuberculosis (TB) disease. Prolonged close contact with cases may lead
to latent TB infection (LTBI). Tuberculin skin sensitivity often indicates LTBI (as noted by a
“positive” skin test), which usually appears four to 12 weeks after infection. LTBI is different
from TB disease and is defined as a condition in which TB bacteria are alive but inactive in the
body. People with latent TB infection have no symptoms and cannot spread TB to others and
usually have a positive skin test reaction. But they may develop TB disease later in life if they do
not receive treatment for latent TB infection.
Approximately 90 percent to 95 percent of newly infected individuals have LTBI where
early lung lesions heal and leave no residual changes except small calcifications in the pulmonary
or tracheobronchial lymph nodes. In those patients whose infection progresses to disease, early
symptoms may include fatigue, fever, night sweats and weight loss. In advanced disease,
symptoms such as cough, chest pain, coughing up blood and hoarseness may occur.
Several issues, such as patients’ immune status and immigration from areas where TB is
common, impact the incidence of the disease in Illinois. The AIDS epidemic had a profound
effect on the number of TB cases in Illinois in the past. TB is a major opportunistic infection in
HIV-infected persons. In Illinois, the percentage of TB cases diagnosed in foreign-born
individuals is increasing. CDC recommends that all immigrants, refugees, foreign-born students
and their families, and others accompanying them into the country be tuberculin-test screened
and medically treated when appropriate.
From 1997 through 2001 in Illinois, 31 percent of TB cases ages 25 to 44 years of age
were positive for HIV. Among the 7,963 AIDS cases reported to IDPH during 1997-2001, TB
was diagnosed in 390 (5 percent) of the cases. Among TB cases reported from 1997 to 2001, 75
percent were pulmonary only, 20 percent extra-pulmonary and 5 percent both. Among HIVpositive cases, 75 percent (173) were pulmonary only, 15 percent (35) were extrapulmonary and
10 percent (23) were both.
Both suspected and confirmed cases of TB are reportable to TB control staff in Illinois.
The sooner cases are reported to the local TB control authority, the sooner personnel can begin
investigations that may interrupt transmission of TB in the community.
Reported Illinois TB cases from 1998 through 2001 totaled 3,108. After excluding 420
persons who stopped therapy for reasons other than treatment completion or death, 10 percent of
the remaining cases (2,688) had death recorded as the reason for not completing therapy.
Compared to cases completing therapy, those who died were older, of U.S. origin, a resident of a
long-term care facility, HIV-infected, had a private provider, had self-administered therapy and
had a non-standard initial drug regimen prescribed.
Case definition
A confirmed case of tuberculosis in Illinois is a case that is either laboratory confirmed or
is a case that meets the clinical case definition criteria:
1)
A positive tuberculin skin test
2)
Other signs and symptoms compatible with tuberculosis, such as an abnormal,
184
3)
4)
unstable chest radiograph, or clinical evidence of current disease
Treatment with two or more anti-tuberculosis medications
Completed diagnostic evaluation
Laboratory criteria for diagnosis are isolation of M. tuberculosis from a clinical specimen,
demonstration of M. tuberculosis from a clinical specimen by DNA probe or mycolic acid pattern
on high-pressure liquid chromatography, or demonstration of acid-fast bacilli in a clinical
specimen when a culture has not been or cannot be obtained.
Descriptive epidemiology
•
Number of cases – In 2001, 707 cases were reported in Illinois, a 5 percent decrease from
2000 (Figure 96). TB cases in Chicago decreased 6 percent with 378 cases in 2001
compared to 403 in 2000.
•
Age – The highest incidence of TB occurred in older age groups (Table 18).
•
Gender – 58 percent were male.
•
Race/ethnicity – 44 percent were African American, 20 percent white and 18 percent
were Asian or Pacific Islander; 18 percent were Hispanic. Asian Pacific Islanders
accounted for 34 percent of cases in suburban Cook County but only 13 percent of cases
in the city of Chicago. African Americans accounted for 55 percent of cases in the city of
Chicago, but only 24 percent of cases in suburban Cook County.
<
The number of foreign-born TB cases increased in 2001 (N=261) compared to
2000 (N=253) (Figure 97). Persons born in India, Mexico and the Philippines
contributed the largest numbers (60 percent) of foreign-born cases in Illinois.
Persons born in Vietnam (6 percent), Pakistan (4 percent), Poland (3 percent) and
China (3 percent) were also represented among foreign-born cases.
•
Risk factors – Excessive use of alcohol (13 percent), non-injection drug use (13
percent), homelessness (3 percent), residing in a long-term care facility (3 percent),
injection drug use (3 percent) and being an inmate in a correctional facility (2 percent)
•
Drug resistance – 13 percent of cases undergoing susceptibility testing were resistant to at
least one drug. Eight percent were resistant to INH and four of 542 tested (0.73 percent)
were multidrug resistant.
•
Death during anti-TB treatment - 42 (7 percent) reported cases died during treatment.
Summary
In 2001, 707 cases of TB were reported in Illinois with an incidence rate of 5.7 per
100,000, which is very similar to the national incidence rate. Thirty-seven percent of these cases
were among persons born outside of this country. Foreign-born persons represent an increasing
percentage of TB cases in Illinois, especially for persons from India, Mexico and the Philippines.
Public health attention must continue to focus on high-risk groups, especially those born outside
of this country. Nationally, 5 percent of cases died during anti-TB treatment vs. 7 percent in
Illinois.
185
Table 18. Age distribution of tuberculosis cases in Illinois, 2001
Age
Incidence *
< 5 years
3.6
5 - 14
0.8
15 - 24
3.9
25-44
6.8
45-64
8.1
65+
7.9
All
5.7
U.S.
5.6
* Incidence per 100,000 based on 2000 population
Source: Illinois Department of Public Health, 2002
186
Figure 97. TB by country of origin, Illinois, 2001
NOTE: Chart on left indicates U.S. vs. foreign-born cases. The chart on the right includes only
foreign-born cases.
Source: Illinois Department of Public Health, 2002
187
Tularemia
Background
Tularemia is a zoonotic infection transmitted by ticks. It is caused by the bacteria
Francisella tularensis. There are four biogroups of tularemia, with two accounting for most
clinical disease. Tularemia can affect more than 250 species of mammals and some birds,
amphibians and reptiles. Natural transmission to persons in the United States is most commonly
through tick bites or direct contact with infected tissue. As few as 10 to 50 organisms can cause
disease in humans. The bacteria can penetrate intact skin. Less common routes of infection
include ingestion, inhalation while shearing infected sheep and exposure to contaminated water.
Tularemia peaks in the summer, reflecting transmission from ticks, and again in winter as the
result of transmission from animal contacts especially rabbits. The most important epizootic
hosts for tularemia in the United States include rodents and lagomorphs.
The most common tick vectors in the United States are the American dog tick
(Dermacentor variabilis), the lone star tick (Amblyomma americanum) and the Rocky Mountain
wood tick (D. andersoni).
The incubation period is three to five days. Clinical signs in humans include fever, chills,
malaise, cough, myalgias, vomiting and fatigue followed by the development of one of six
clinical syndromes: ulceroglandular, glandular, typhoidal, pleuropulmonary, oculoglandular or
oropharyngeal tularemia. Ulceroglandular is the most common form of tularemia, occurring in
about 80 percent of cases. Isolation of F. tularensis requires biosafety level 3 facilities.
Tularemia is considered a possible bioterrorism agent. Vaccination is recommended only for
limited numbers of persons in high-risk occupations.
A CDC study of tularemia cases reported from 1990 to 2000 identified 1,368 cases, most
(56 percent) of them in four states (Arkansas, Missouri, Oklahoma and South Dakota). The
highest incidence occurred in people ages 5 to 9 years and in those older than 75 years of age.
Males had a higher incidence than females. Seventy percent of cases were reported from May to
August. An outbreak of pneumonic tularemia occurred on Martha’s Vineyard, Massachusetts in
2000; 15 cases were identified. Cases were more likely than controls to have used a lawn mower
or brush cutter in the two weeks before illness.
In 2001, 129 cases were reported to CDC. Illinois was the state with the second highest
number of cases (14 cases) after Missouri (27 cases).
Case definition
The CDC case definition for a confirmed case of tularemia is either isolation of F.
tularensis from a clinical specimen or a four-fold or greater rise in serum antibody titer to F.
tularensis antigen. A probable case is a clinically compatible case with either detection of F.
tularensis in a clinical specimen by fluorescent antibody or an elevated serum antibody titer to F.
tularensis antigen in a patient with no history of vaccination.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 14
•
Age – Ages ranged from 6 to 70 years of age.
•
Gender – Two cases were female.
•
Seasonal variation – Onsets of 13 cases occurred from April to October. One case
188
•
•
<
became ill in January. Month of onset for cases from 1997 through 2001 is shown in
Figure 98. The majority of cases occur in the summer months, which is consistent with
probable transmission from ticks.
Geographic distribution – Exposure sites for cases were Bond County (2), Macon County
(2), Richland County (2) and Sangamon County (2). There was one case in each of the
following counties: Cook, Johnson, Macoupin, Madison, Randolph and St. Clair.
Symptoms/diagnosis/treatment – Cases reported symptoms including fever (8), swollen
lymph nodes (7), fatigue (4), erythematous rash (3), diarrhea (2), headache (2), inflamed
and slow healing wounds (2), abdominal soreness (1), ataxia (1), delirium (1), joint pain
(1), muscle pain (1), scleral icterus (1) and sore throat (1). Eight cases reported tick bites
prior to onset of illness and one person noticed a bite after onset. Other possible
exposures included contact with domestic animals (2), an animal bite (1), and obtaining a
cut while skinning an animal (1). A source of exposure could not be determined for one
case. Four cases were culture positive, nine were serologically positive and one was
unknown.
Past incidence – The number of cases in Illinois by year are as follows: 1991 (5), 1992
(2), 1993 (3), 1994 (3), 1995 (4), 1996 (4), 1997 (5), 1998 (5), 1999 (2), 2000 (4) and
2001 (14).
Summary
The number of cases of tularemia was more than double in 2001 compared to the five-year
median of four cases per year. It is unknown whether this was due to improved reporting or an
actual increase in the number of cases in the state. The state of Illinois had the second highest
number of cases in 2001, after Missorui. Most cases in Illinois have onset of illness during the
tick transmission season, which is consistent with U.S. data from CDC.
Suggested readings
Feldman KA. Tularemia. J. Am. Vet. Med. Assoc. 2003;222(6):725-30.
Feldman KA et al. An outbreak of primary pneumonic tularemia on Martha’s Vineyard.
NEJM 2001;345(22):1601-6.
Hechemy KE. Tularemia. FROM. Encyclopedia of arthropod-transmitted infections of
man and domesticated animals. CABI Publishing. 2001. Pp535-8.
MMWR. Tularemia-United States, 1990-2000. MMWR 2002;51(9): 181-4.
MMWR. Summary of notifiable diseases - United States, 2001. MMWR 2003; 50(53): p.
12.
Zaidi SA, Singer C. Gastrointestinal and hepatic manifestations of tickborne diseases in
the United States. CID 2002;34:1206-12.
189
190
Typhoid fever
Background
Typhoid fever is a systemic infection caused by infection with Salmonella enterica
serotype Typhi. The incubation period is from three days to three months with a usual range of
one to three weeks. Transmission of typhoid fever is usually by ingestion of food or water
contaminated by fecal or urinary carriers of S. enterica ser. Typhi. Types of products implicated in
some countries include shellfish, raw fruits, vegetables and contaminated milk or milk products.
Unlike other types of Salmonella, S. enterica ser. Typhi is not found in animal reservoirs; humans
are the only reservoirs. In developed countries like the United States, most cases are sporadic after
travel to endemic areas. The infectious dose ranges from 1,000 to 1 million organisms.
Constipation is more common than diarrhea in adults. The onset of bacteremia with typhoid fever
results in fever, headache, abdominal discomfort, dry cough and myalgia. Other findings may
include bradycardia, rash and splenomegaly. Complications may include gastrointestinal bleeding,
intestinal perforation and typhoid encephalopathy. Relapse may occur in 5 percent to 10 percent
of patients, usually two to three weeks after resolution of fever. Up to 10 percent of untreated
patients will shed organisms in the feces for up to three months. A small number (1 percent- 4
percent) carry the organism up to one year. Most carriers are asymptomatic. Chronic carriage is
more common in women, the elderly and in patients with cholelithiasis.
Typhoid fever is typically diagnosed with blood cultures. Bone marrow cultures also can
be used. For travelers to developing countries, water should be boiled or bottled and food should
be thoroughly cooked to avoid acquiring typhoid fever. Vaccination is recommended for persons
traveling to areas where typhoid is endemic.
In 2001, 368 typhoid fever cases were reported in the United States. Approximately 80
percent of cases reported international travel in the six weeks before illness.
Case definition
A confirmed case is a clinically compatible illness with isolation of S. enterica ser. Typhi
from blood, stool or other clinical specimen. A probable case is defined as a clinically compatible
illness that is epidemiologically linked to a confirmed case in an outbreak.
Descriptive epidemiology
•
Number of cases reported in Illinois in 2001 – 18 (five-year median = 26) (Figure 99); two
were acquired in the U.S.
•
Age – Cases ranged in age from infant to 57 years (median age = 10 years).
•
Seasonal variation – Cases occurred throughout the year.
•
Geographic distribution – Of the 18 cases, 12 (67 percent) resided in Cook County.
•
Case surveillance reports – The following information was drawn from 18 case reports:
<
Citizenship status – Eight cases were known to be citizens of the United States and
four were not; the citizenship status of six cases was unknown.
<
Employment – One case was known to be a food handler.
<
Treatment/outcomes – 10 of 15 cases (67 percent) with available information were
hospitalized.
<
Drug resistance – Resistance characteristics of isolates were known for 11 cases.
These 11 isolates showed resistance to ampicillin (3 of 10 tested, 30 percent),
chloramphenicol (0 of 3, 0 percent), trimethoprim-sulfamethoxazole (2 of 9, 22
191
<
<
percent) and fluoroquinolones (1 of 7, 14 percent).
Vaccination status – Only one case reported having received typhoid vaccination
within five years of illness onset.
Risk factors – No cases were known to have been linked to a typhoid carrier.
Travel destinations for imported cases included India (8), Pakistan (3), Mexico (2),
Ghana (1), Nigeria (1) and Philippines (1). Most individuals who traveled did so
for the purpose of visiting relatives.
Summary
There were 18 typhoid fever cases reported in Illinois in 2001. However, the majority of
cases were acquired outside the U.S. India was the most common travel destination for those
cases who reported travel outside the U.S.
Suggested readings
Parry CM, Hien TT et al. Typhoid fever. NEJM 2002;347(22):1770-82.
MMWR. Summary of notifiable diseases-United States, 2001. MMWR
2003;50(53):p.xxiii-xxiv.
192
Varicella (chickenpox)
Background
Chickenpox (varicella) caused by varicella-zoster virus is characterized by sudden onset
of slight fever and a rash. Lesions present with successive crops and several stages of maturity
present at the same time. Serious complications of varicella may occur and can include
pneumonia, secondary bacterial infections, hemorrhagic complications and encephalitis. Herpes
zoster (shingles) is a local manifestation of reactivation of latent varicella in dorsal root ganglia.
Severe pain and paresthesia may accompany this manifestation.
The incubation is two to three weeks long. A person is communicable as long as five days
before rash onset and remains infectious until the rash is crusted over. The disease is transmitted
through direct contact between persons, droplet or airborne spread of vesicle fluid or respiratory
tract secretions or indirectly through fomites.
In 1995, a live attenuated varicella vaccine became available for use in the U.S. A single
dose is recommended for children ages 12 to 18 months, and for children up to 12 years of age
who have not yet had varicella. Supplies of varicella vaccine were limited and back orders were
common in 2001. Varicella related deaths became nationally notifiable in 1999 to allow for
evaluation of the vaccine program. In Illinois, individual cases of adult varicella became
reportable in February 2002, partly to allow for rapid identification of possible smallpox cases in
the event of a bioterrorism event. Varicella might be confused with smallpox in adults.
Case definition
Physician diagnosed cases are reported to IDPH with a weekly summary from local health
jurisdictions. Individual cases are not reported.
Descriptive Epidemiology
•
Number of cases – 10,653 (median=16,459) (Figure 100)
•
Age – Almost three-quarters of cases occurred in individuals between the ages of 5 and 14
years.
An outbreak of varicella was reported among children attending school in Winnebago
County from January through May 2001. The outbreak involved children at two elementary
schools. Five hundred children attended the two schools. Thirty-five children with varicella were
identified and eight had breakthrough varicella (varicella in spite of vaccination). The attack rate
among unvaccinated children was 30 percent in one school and 54 percent at the other school. The
overall varicella vaccine efficacy was found to be 88 percent. Reasons for not vaccinating children
who did not have a history of varicella were vaccine was not recommended by pediatrician (18
percent), vaccine was too new or needed more research (13 percent), parent had lack of
knowledge of or access to the vaccine (11 percent), parent was concerned about the duration of
immunity provided by the vaccine vs. natural immunity (17 percent), the parent was concerned
about too many vaccinations (1 percent), and no response or no reason (40 percent). Vaccination
of children younger than 15 months of age was associated with an increased risk for breakthrough
varicella.
193
Summary
Varicella (chickenpox) is reportable in aggregate in Illinois and more than 10,000 cases
were reported in 2001. The number of reported chickenpox cases has been declining since 1996.
Suggested readings
Dworkin MS et al. An outbreak of varicella among children attending preschool and
elementary school in Illinois.
Galil K et. al. Tracking varicella deaths: Accuracy and completeness of death certificates
and hospital discharge records, New York state, 1989-1995. AJPH 2002;92-9):1248-50.
194
Yersiniosis
Background
Yersiniosis, an infrequently reported cause of diarrhea in the United States, is caused by
Yersinia enterocolitica or Y. pseudotuberculosis. Transmission is by the fecal-oral route, through
consumption of contaminated food or water, or by contact with infected people or animals. The
incubation period is three to seven days. Fecal shedding occurs for as long as symptoms are
present, usually two to three weeks. Manifestations of the disease include an acute febrile diarrhea
and abdominal pain. Symptoms can mimic appendicitis. Bloody diarrhea is seen in 10 percent to
30 percent of children infected with Y. enterocolitica. The pig is the primary reservoir of Y.
enterocolitica; rodents are the main reservoirs for Y. pseudotuberculosis. Most pathogenic strains
of Y. enterocolitica have been isolated from raw pork or pork products. Chitterling consumption
or contact with someone preparing chitterlings is a common exposure history for those with
yersiniosis. Yersinia is cold tolerant and can replicate under refrigeration. Yersiniosis became
reportable in Illinois on April 1, 2001. Prior to this time, reporting was voluntary.
Of the 10 diseases (those caused by Campylobacter, Cryptosporidium, Cyclospora, E. coli
O157:H7, HUS, Listeria monocytogenes, Salmonella, Shigella, Vibrio and Yersinia
enterocolitica) under active surveillance in the federal FoodNet sites, Yersinia comprised 1
percent of the reported infections in data from 2001. The incidence rate per 100,000 for
yersiniosis in 2001 preliminary data ranged from 0.3 to 0.6 at the FoodNet sites.
Case definition
The case definition in Illinois is a person with a positive culture for Yersinia.
Descriptive epidemiology
•
Number of reported cases in Illinois in 2001 – 38 (five-year median = 24) (see Figure
101). The incidence rate per 100,000 was 0.3.
•
Age – 17 cases (45 percent) occurred in those younger than 5 years of age (Figure 102).
•
Gender – 58 percent were male.
•
Race/ethnicity – 19 percent were African American, 75 percent white and 6 percent Asian.
Summary
Reporting for yersiniosis in Illinois became mandatory on April 1, 2001. The number of
reported cases was higher than during the previous five-year median when reporting was
voluntary. However, the incidence rate for 2001 was similar to that found in the CDC’s FoodNet
sites. Approximately one-third of cases in 2001 occurred in children younger than 5 years of age.
Two of four African-American infants less than 1 year of age had illness onset in December, a
time when traditional meals may include chitterlings, a source of Yersinia.
Suggested readings
MMWR. Preliminary FoodNet data on the incidence of foodborne illnesses-Selected sites,
United States, 2001. MMWR 2002; 51(15): 325-329.
195
196
Other incidents of interest, 2001
Several clusters of Norovirus occurred in 2001 in long-term care settings. One outbreak occurred
in Madison County at a state facility in March. Two stool specimens submitted for testing were
positive for Norovirus, G2, P2-B. Eleven of 38 patients and six employees reported illnesses.
Spread may have been from person to person. In November, an outbreak was reported in a
Sangamon County facility for the developmentally disabled. Two of three stool specimens were
positive for Norovirus. The outbreak appears to have spread by person-to-person transmission.
In July 2001, a high-risk nursery in a Chicago area hospital reported three methicillin resistant S.
aureus (MRSA) infections in infants. Two of three infants were positive from sterile sites. The
nursery was closed to new admissions and transfer of babies was prohibited; babies were cultured
for asymptomatic infections, and the environment and staff were cultured. One environmental
sample was positive and one baby was asymptomatically positive.
197
Table 19. Reported cases of infectious diseases in Illinois, 2001
Disease
Number
Acquired immune deficiency syndrome
Disease
1,212
Amebiasis case
65
Human immunodeficiency virus
Legionnaires’ disease
Number
1,542
24
Anthrax
0
Leprosy
1
Arbovirus infection
5
Leptospirosis
0
Aseptic meningitis or encephalitis of unknown
etiology
1,380
Listeriosis
24
Lyme disease
32
47
Malaria
71
Botulism
0
Measles
3
Brucellosis
4
Meningococcal, invasive
Aseptic meningitis or encephalitis of known etiology
177
Blastomycosis
Campylobacteriosis
1,265
Murine typhus
88
2
Chickenpox
10,653
Mumps
21
Chlamydia trachomatis
43,716
Pertussis
194
Cholera
0
Cryptosporidiosis
483
Psittacosis
Rabies, animal
24
96
Cyclospora
2
Rabies, potential human exposure
Cysticercosis
3
Reye syndrome
Dengue
2
Rocky Mountain spotted fever
Diphtheria
0
Rubella
Ehrlichiosis, human granulocytic
1
Salmonellosis
Ehrlichiosis, human monocytic
3
Shigellosis
Ehrlichiosis, unknown type
3
S. aureus, vancomycin resistant
E. coli O157:H7
Foodborne or waterborne outbreaks
Giardiasis case
Gonorrhea
2
1,383
630
0
272
75
Streptococcus, group B, invasive
65
8
103
Hantavirus
12
Streptococcus, group A, invasive
24,025
H. influenzae, invasive disease
0
173
904
Guillain Barre syndrome
0
0
S. pneumoniae, invasive
491
Syphilis, primary or secondary
409
Tetanus
2
Toxic shock syndrome
4
Trichinosis
1
Hepatitis A case
441
Tuberculosis
Hepatitis B case
218
Tularemia
14
12
Typhoid fever case
18
98
Yersiniosis
38
Hepatitis NANB case
Histoplasmosis
Source: Illinois Department of Public Health, 2002
198
707
Methods
Health care professionals – including infection control nurses, physicians and school
nurses – are required by Illinois law to report specific infectious diseases to their local health
department. There are 94 local health departments in Illinois. Some serve a city or district, some
serve the entire county and some serve residents of several counties. The local health department
reports cases to the Illinois Department of Public Health (IDPH), which, in turn, reports all
nationally notifiable diseases to the U.S. Centers for Disease Control and Prevention (CDC). All
information about patients is confidential; case reports to the CDC do not identify patients.
This annual report includes only cases reported to IDPH. Therefore, these annual
numbers will underestimate the total number of cases of each disease in the state. Some
patients with disease do not seek medical attention, some may not have the necessary testing done
for a diagnosis, or the medical provider may not report the case to public health authorities. Also,
to standardize reporting in the state, only cases that are reported and meet the case definition for
that disease are included in case counts. For some diseases, a case definition is listed for both
confirmed and probable cases. For all diseases except HIV/AIDS, the number of cases reported in
a year is “closed out” on April 1 of the following year. If cases from the preceding year are
reported after April 1, they are not included in the preceding year’s numbers. Instead, they are
included in the following year’s numbers. For HIV/AIDS, there are two categories: number of
cases reported in a given year vs. number of cases diagnosed in a given year. The number of cases
diagnosed in a given year is continually updated even if there is an extremely long delay in
reporting a case. Therefore, the numbers for diagnosed AIDS cases in 2000 may be updated.
Reportable diseases diagnosed in college students living away from home and in residents
of prisons, long-term care or other residential facilities are reported in the jurisdiction where the
patient resides at the time of diagnosis. This results in attributing to rural counties that have a
college or prison high incidence rates of certain diseases. Persons who are residents of Illinois but
are not citizens of the United States may be counted. Persons who are visiting the United States
and become clinically ill with malaria are counted in malaria statistics. Residents of other states
who become ill in Illinois are not counted in this state’s statistics but are transferred to the state of
residence. However, temporary workers in Illinois are counted in the state’s statistics.
The Illinois population used to calculate incidence rates and race and ethnicity proportions
in past editions of this document was from the 1990 Modified Age-Race-Sex (MARS) data. This
is the first infectious disease annual report that has used the 2000 census numbers. According to
the U.S. Census Bureau, Illinois’ population grew from 11,430,602 in 1990 to 12,419,293 in
2000. The percentage of the population in the various age groups changed very little between the
1990 MARS data and the 2000 census. However, the racial and ethnic distribution did change
substantially between 1990 and 2000. In 1990, the state’s population was 82 percent white, 15
percent African American, 2 percent Asian and 1 percent other or mixed races. In 2000, the
census found the following percentages: 73 percent white, 15 percent African American, 3 percent
Asian and 8 percent other or mixed races. Those indicating Hispanic ethnicity accounted for 8
percent of the state’s population in 1990; in 2000, this proportion had increased to 12 percent. In
2000, 49 percent of the population was male and 51 percent was female. The following table
shows the age distribution of the Illinois population as determined by the 2000 census.
199
Table 20. 2000 Illinois census data by age category
Age category
Census
numbers used
for 2000 annual
report
% of population
<1 year
173,373
1
1-4 years
703,176
6
5-9 years
929,858
7
10-19 years
1,799,099
14
20-29 years
1,742,602
14
30-59 years
5,108,274
41
>59 years
1,962,911
15
TOTAL
12,419,293
Source: Illinois Department of Public Health, 2002
Where it was deemed useful, graphs were produced showing the number of cases by
month, the number of cases by year since 1995 and the age distribution. Incidence rates were
calculated by age for diseases in which more than 150 cases occurred. One-year incidence rates by
county were graphed for giardiasis, hepatitis A, salmonellosis and shigellosis. Incidence rate was
calculated by taking the number of cases in a category, dividing by population size from 2000
census data and multiplying by 100,000. If an annual incidence rate was calculated for the period
1996 to 2000, it was reached by taking the number of cases reported from 1996 through 2000,
dividing by the population and multiplying by 100,000; it was then annualized by dividing by five.
The epidemiologic information presented for each disease is for 2001 only, unless
otherwise specified. For some diseases, where the number of cases by year was low, information
may have been combined for multiple years to allow demonstration of trends by month and age.
When the case population differed from the Illinois population in the racial distribution, a chisquare test for a significant difference in proportions was done using the Epi-Info software
package. Means were reported when the data followed a normal distribution; otherwise, the
median was reported.
Suggested reading lists are provided for some diseases.
200