Download Norwalk, Rabies - Spokane Regional Health District

COMMUNICABLE DISEASE NEWS
Art for art’s sake? I should think so, and more so than
ever at the present time. It is the one orderly product
which our middling race has produced. It is the cry of a
thousand sentinels, the echo from a thousand labyrinths,
it is the lighthouse which cannot be hidden … it is the
best evidence we can have of our dignity.
E E p i gr am
„
SPOKANE REGIONAL HEALTH DISTRICT
1101 West College Avenue
Spokane, WA 99201-2095
E. M. Forster (1879–1970)
FEBRUARY 2002
Norwalk in the News
Here in these United States, only the common cold is
reported more frequently than viral gastroenteritis as a
cause of illness. Although viral gastroenteritis is caused
by a number of viruses, it is estimated that Norwalk-like
viruses are responsible for about 1/3 of the cases of
gastroenteritis in those over 2 years of age. These
viruses, also known as small round structured viruses or
caliciviruses, are typically named for the location in
which they were first identified, for example, Hawaii,
Snow Mountain, Montgomery County and Oklahoma
and the Norwalk virus is their prototype.
In developing countries the percentage of individuals
who have developed immunity at an early age is very
high. In the U.S., the percentage increases gradually with
age, reaching 50% in the population over 18. Immunity,
however, is not permanent and reinfection can occur. All
individuals who ingest the virus and who have not had
an infection with the same or related strain within the
previous 12-24 months are susceptible and can develop
gastroenteritis. The infectious dose is unknown but
presumed to be low.
The signs and symptoms of Norwalk-like viruses are
similar and usually occur 24 - 48 hours after exposure.
They include nausea, vomiting, diarrhea, abdominal
pain, muscle aches, headache, fatigue and low-grade
fever. Symptoms typically last 24 - 48 hours and subside
on their own. There are no known long- term effects
after recovery from this infection.
Until recently, it was though that humans were the only
source for Norwalk-like viruses, but they have been
found to occur often in calves and sometimes in pigs.
The viruses are present in the feces of infected persons
and can be readily transmitted to others when hands are
not thoroughly washed after toileting. Asymptomatic
carriage can occur for up to 4 weeks after illness.
Raw and incompletely cooked shellfish as well as salad
ingredients are the foods most often implicated in
Norwalk outbreaks. People also can be infected by
drinking water contaminated by sewage containing one
of these viruses or by consuming ice made from
contaminated water. There is some evidence that the
viruses also can be transmitted by aerosolized vomitus.
The objective of treatment is to replace fluids and
electrolytes. People with diarrhea who are unable to take
fluids by mouth because of nausea may need intravenous
fluids, especially small children. Antidiarrheal
medications are generally not given, as they may
prolong the infectious process. Antibiotic therapy is not
effective.
The U.S. Centers for Disease Control and Prevention
estimates that more than 180,000 cases of Norwalk-like
virus infections occur annually in the United States.
When these viruses are recognized, it is usually because
they are associated with an outbreak of gastrointestinal
illness. Standard hospital laboratories and commercial
laboratories usually are not equipped to detect Norwalklike viruses. The specialized laboratories that can detect
these viruses perform tests on stool specimens and, in
some cases, can identify evidence of infection by testing
blood for antibody.
Research trials on a Norwalk virus plant-based vaccine
being conducted at several universities in the U.S. show
initial success, with participants developing an immune
response to the vaccine. Stay tuned.
Rabies in Washington State
In November, the first case of terrestrial animal rabies
since 1994 in Washington State was confirmed at the
State Public Health Laboratories and the Centers for
Disease Control and Prevention (CDC). The affected
animal, an unvaccinated cat from Walla Walla county,
may have been exposed to a rabid bat; further testing is
being conducted at the CDC. This case emphasizes the
importance of vaccinating pets and taking appropriate
precautions when humans are potentially exposed to
rabies, including reporting bites to SRHD. Each case is
investigated by SRHD staff in collaboration with Animal
Control, with the dual purposes of 1) location and
confinement or testing of the animal and 2) evaluation of
the exposure risk of the victim. If an animal under
observation for 10 days shows no sign of disease, postexposure prophylaxis (PEP) is generally not
recommended. If a decision has been made to euthanize
the animal, it can be tested quickly for the presence of
the rabies virus if the head has been properly preserved.
In most cases, observation and/or testing can prevent
costly and lengthy PEP. PEP is effective if administered
within 14 days of the bite incident, so there is no
urgency to begin the series before the results of the
testing or the observation period is complete.
Rabies in Washington is almost invariably transmitted
by rabid bats. The last rabid animal that was not a bat
was a llama, infected in 1994 in King County, through
the bite of an infected bat. The last rabid cat occurred in
Thurston County, in 1976, and was presumably infected
by a bat. (Testing at the time was not sophisticated
enough to determine the strain of the rabies virus.) The
last human case of rabies occurred in 1996, following
infection with bat strain rabies in a 64 year old Mason
county man. He lived in a rural area, and had recently
cleaned out a shed, but the family was not aware of any
specific exposure to bats.
In the Walla Walla case, members of the family who
owned the cat and were scratched, bitten, or exposed to
the cat's saliva received PEP to prevent rabies, as did a
neighbor and several staff in a veterinary clinic where
the cat was taken after becoming ill. The family also
owns two dogs that have not been recently vaccinated
against rabies. The dogs are quarantined for six months
because of the risk that they may have been exposed to
the rabid cat.
Rabies control in animals relies on the routine
vaccination of animals for which vaccine is available.
Rabies immunization should be current for all domestic
dogs, cat and ferrets. Vaccine efficacy in captured wild
animals or hybrids (pet raccoons, skunks, wolf-dog) is
unknown, and keeping these animals is not
recommended. Dogs, cats or ferrets that bite humans
should be observed for 10 days or euthanized and
examined for rabies.
Cases of Selected Diseases Reported to Spokane Regional Health District—Jan 2002
DISEASE
AIDS
*Cumulative – 405 (as of Dec 2001)
THIS
MONTH
(January 2002)
**
LAST
MONTH
(Dec 2001)
**1
LAST YEAR
TO DATE
(Dec 2001)
**22
THIS YEAR
TO DATE
(January 2002)
**
Borreliosis (Relapsing Fever)
0
0
0
0
Campylobacteriosis
4
4
9 41
4
48
60
720
48
Chlamydial STD
Enterohemorrhagic E Coli (including 0157:H7)
1
0
9 12
1
Giardiasis
3
5
9 63
3
Gonorrhea
16
9
94
16
Hepatitis A acute
2
0
3
2
Hepatitis B acute
3
4
34
3
Hepatitis B chronic
Hepatitis C acute and chronic
HIV
*Cumulative – 101 (as of Dec 2001)
Influenza (Sep 1 – Aug 31)
9
3
62
9
74
42
799
74
NA
NA
NA
NA
3
0
0
3
Measles (Rubeola, Red)
0
0
0
0
Meningococcal Disease
0
0
7
0
Mumps
0
0
0
0
Pertussis (Whooping Cough)
0
0
1
0
Rubella (German Measles)
0
0
0
0
Salmonellosis
2
10
9 43
2
Shigellosis
0
0
6
0
Syphilis
0
0
3
0
**0
**0
**11
**counts generated by State DOH are one month delayed
9 includes case reports for previous months to correct year-end totals
**0
Tuberculosis** (as of Nov 2001)