Download Introduction to Infectious Disease Epidemiology

Introduction to Infectious Disease
Epidemiology
- STDs Hsci 436 – Health Concerns of the
Adolescent
Dr. E. Frank Spinello
Pathogens
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Bacterial
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Viral
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yeast infections, Candida
Protozoa
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tapeworms, trichinosis, schistosomes
Fungal
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Organic and inorganic
Allergens, carcinegens, neurotoxins, teratogens
Parasitic (multi-cell)
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About 230 million HIV on the head of a pin.
Not affected by antibiotics
Chemical toxins
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About 1 million on the head of a pin
Salmonella, botulism, anthrax
Single cell organisms
Prions
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Relatively new discovery
Infectious agent with protein-like qualities
Thought to be responsible for BSE (mad cow disease) and vCJD
Difficult to disinfect
Historical Overview
• Traditionally, infectious disease was the
biggest health threat to human civilization.
• As medical technology and public health
reduced the threat of infectious diseases,
lifespans increased to the point of making
chronic diseases more prevalent.
Infectious Diseases in History
• In the mid-1300’s about 23 million people
in Europe died from plague.
– Plague-related deaths represented 10-15% of
each new generation for a period of about 100
years.
– The population shifts changed the cultural and
political makeup of Europe
Influenza
• By many estimates, major flu outbreaks occur
about every 11 years.
• The 1918 flu pandemic killed 50-100 million
people within about 18 months.
– More people died worldwide than in all of the wars of
the 20th century, combined.
• The 1976 swine flu scare resulted in a national
immunization program.
– The fear was that the swine flu was a close variant of
the 1918 virus and would trigger another pandemic.
Syphilis
• Is thought to have been brought back by
Columbus’ crew from the New World to
Europe.
– Often treated with mercury, which resulted in
many individuals with mercury poisoning.
HIV/AIDS
• Human Immunodeficiency Virus was first
detected in 1980.
– Confirmed index patient was a Canadian flight
steward.
– The earliest known case may date back to
1958.
New Concerns
• Increased frequency of travel combined with
short travel times mean that pathogens are no
longer geographically isolated
– One reason that Ebola has never spread has been
the remote areas in which it is found.
• MDRs – Multiple drug resistant bacterial strains.
– A variety of bacteria no longer respond to traditional
antibiotics as they have begun to mutate and adapt.
– Partially due to inappropriate antibiotic use.
Sexually Transmitted Diseases
• Most common include:
– Chlamydia
– Syphilis
– Gonorrhea
– Genital herpes
– Genital warts (caused by the human
papillomavirus)
– Hepatitis B
PID Complications
• Pelvic Inflammatory Disease (PID) is a common
complication of many STD’s in women:
– May be asymptomatic
– When symptoms are present, they can be very severe
and can include abdominal pain and fever
– abscesses (pus-filled “pockets” that are hard to cure)
and long-lasting, chronic pelvic pain
– can damage the fallopian tubes enough to cause
infertility or increase the risk of ectopic pregnancy
Chlamydia
• Caused by the bacterium, Chlamydia
trachomatis
• The most frequently reported bacterial sexually
transmitted disease in the United States
• Often undiagnosed due to lack of initial
symptoms
– about three quarters of infected women and about
half of infected men have no symptoms. If symptoms
do occur, they usually appear within 1 to 3 weeks
after exposure.
• Symptoms include pain, discharge, bleeding.
Chlamydia
• Untreated women
– About 40% of women develop PID
– Can cause permanent damage to fallopian tubes,
uterus, and surrounding tissue
– 5 times more likely to become HIV infected if
exposed.
– Chlamydia is a leading cause of early infant
pneumonia and conjunctivitis (pink eye) in newborns.
• Untreated men
– Complications are rare
– Sterility, eye infections, arthritis, skin lesions
Chlamydia
• Diagnosis
– Urine or discharge specimen
• Treatment
– A single dose of azithromycin or a week of doxycycline (twice
daily) are the most commonly used treatments.
• Prevention
– Retesting should be considered for women, especially
adolescents, three to four months after treatment. This is
especially true if a woman does not know if her sex partner
received treatment.
– Condoms can reduce infection risk
– Upon diagnosis, all sex partners must be notified
Syphilis
• Caused by the bacterium Treponema pallidum. It
has often been called “the great imitator”
because so many of the signs and symptoms
are indistinguishable from those of other
diseases.
• Most cases occur in people age 20 to 39
• About 3.5x more men than women
• Rates are decreasing in women but increasing
about 12.5% in men due to MSM
Syphilis
• Transmission
– Direct contact with syphilis sore
– Genitals, lips, and mouth
• Symptoms
– ES may not present symptoms for years
– Primary stage
• Initial sore at point of contact w/in 90 days, heals w/o treatment
– Secondary Stage
• Non-itchy rash (appearing as red blotches or spots) on genitals, hands and
feet
• Swollen glands, hair loss, headaches, weight loss, muscle aches, fatigue
– Latent syphilis
• Initial symptoms disappear
• Up to years later -- damage to internal organs and brain, nerves, eyes,
heart, blood vessels, liver, bones, and joints
• Symptoms include: difficulty coordinating muscle movements, paralysis,
numbness, gradual blindness, and dementia, and death
Syphilis
• Diagnosis
– Requires smear from cancre sore.
• Dark field microscopy is used
• Blood test to detect antibodies
• Implications
– Genital sores (chancres) caused by syphilis
make it easier to transmit and acquire HIV
infection sexually. There is an estimated 2- to
5-fold increased risk of acquiring HIV infection
when syphilis is present.
Syphilis
• Treatment
– Syphilis is easy to cure in its early stages. A
single intramuscular injection of penicillin, an
antibiotic, will cure a person who has had
syphilis for less than a year.
• Prevention
– Abstinence
– Avoid risky behavior
– Condom use, although N9 spermicide may
cause lesions and increase risk.
Gonorrhea
• caused by Neisseria gonorrhoeae, a
bacterium that can grow and multiply
easily in the warm, moist areas of the
reproductive tract, including the cervix
(opening to the womb), uterus (womb),
and fallopian tubes (egg canals) in
women, and in the urethra (urine canal) in
women and men. The bacterium can also
grow in the mouth, throat, eyes, and anus.
Gonorrhea: Overview
• CDC estimates that more than 700,000
persons in the U.S. get new gonorrheal
infections each year.
– About ½ are reported to CDC
• Transmission
– Sexual contact
– Highest reported rates of infection are among
sexually active teenagers, young adults, and
African Americans.
Gonorrhea: Signs and Symptoms
• Males
– May have no symptoms at all
– 5 to 30 days after infection:
• Burning sensation during urination
• White, yellow, or green discharge
• Swollen/painful testicals (not all)
• Females
– Most have no symptoms
– Often non-specific and mistaken for bladder or yeast infection
– Initial symptoms and signs in women include a painful or burning
sensation when urinating, increased vaginal discharge, or
vaginal bleeding between periods
– Sore throat
Gonorrhea: Complications
• Males
– gonorrhea can cause epididymitis, a painful condition
of the testicles that can lead to infertility if left
untreated
– can spread to the blood or joints
– Increases risk of HIV infection
• Females
– PID - abdominal pain and fever
– can spread to the blood or joints
– Increases risk of HIV infection
Gonorrhea: Treatment and
Prevention
• Diagnosis
– Doctors office can perform a Gram stain of a
sample from a urethra or a cervix allows the
doctor to see the gonorrhea bacterium under
a microscope
• Treatment
– Multiple antibiotics are generally used due to
co-morbidity with chlamydia
– Resistant strains are now being increasingly
encountered
Hepatitis B
• Viral infection passed through bodily fluids from one
person to another.
• High Risk Groups:
– Persons with multiple sex partners or diagnosis of a sexually
transmitted disease
– MSM
– Sex contacts of infected persons
– Injection drug users
– Household contacts of chronically infected persons
– Infants born to infected mothers
– Infants/children of immigrants from areas with high rates of HBV
infection (view map)
– Health care and public safety workers
Hemodialysis patients
Source: U.S. Centers for Disease Control
Hepatitis B - Prevalence
• Number of new infections per year has declined
from an average of 260,000 in the 1980s to
about 78,000 in 2001.
• Highest rate of disease occurs in 20-49-yearolds.
• Greatest decline has happened among children
and adolescents due to routine hepatitis B
vaccination.
• Estimated 1.25 million chronically infected
Americans, of whom 20-30% acquired their
infection in childhood.
Hepatitis B – Signs and Symptoms
• About 30% have no symptoms
• Symptoms include:
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jaundice
fatigue
abdominal pain
loss of appetite
nausea, vomiting
joint pain
• Death from chronic liver disease occurs in 1525% of chronically infected persons
Hepatitis B - Treatment
• Adefovir dipivoxil, alpha interferon, and
lamivudine are three drugs licensed for the
treatment of persons with chronic hepatitis B.
• These drugs should not be used by pregnant
women.
• Drinking alcohol can make your liver disease
worse.
Hepatitis B – Prevention
• Vaccination is best defense for high-risk
individuals. Recommended for public
health and public safety workers.
• Effectiveness of condom use is unknown
but they are likely to help protect against it.
• Reduce IV drug use / syringe sharing
• Discourage sharing of personal items
(razors, etc.)
• Consider risks of tattoos and body piercing
Genital Herpes - Overview
• Genital herpes is a sexually transmitted disease (STD) caused by
the herpes simplex viruses type 1 (HSV-1) and type 2 (HSV-2).
• Most genital herpes is caused by HSV-2. Most individuals have no
or only minimal signs or symptoms from HSV-1 or HSV-2 infection.
When signs do occur, they typically appear as one or more blisters
on or around the genitals or rectum. The blisters break, leaving
tender ulcers (sores) that may take two to four weeks to heal the first
time they occur. Typically, another outbreak can appear weeks or
months after the first, but it almost always is less severe and shorter
than the first outbreak. Although the infection can stay in the body
indefinitely, the number of outbreaks tends to decrease over a
period of years.
Genital Herpes
• Prevalence
– 45 million people ages 12 and older,
– one out of five adolescents and adults, have had genital HSV
infection.
– Between the late 1970s and the early 1990s, the number of
Americans with genital herpes infection increased 30 percent.
– Genital HSV-2 infection is more common in women
• approximately one out of four women
• almost one out of five men
• This may be due to male-to-female transmissions being more likely
than female-to-male transmission.
– HSV-1 can cause genital herpes, but it more commonly causes
infections of the mouth and lips, so-called “fever blisters.” HSV-1
infection of the genitals can be caused by oral-genital or genitalgenital contact with a person who has HSV-1 infection. Genital
HSV-1 outbreaks recur less regularly than genital HSV-2
outbreaks.
Genital Herpes – Signs and Symptoms
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Most HSV-2 people are not aware of first infection.
First outbreak is generally 1-2 weeks after infection and may last 3-4 weeks.
– First outbreak is generally accompied with swollen glands, fever, flu-like
symptoms.
– 4 to 5 five outbreaks in the first year, with decreasing frequency thereafter.
– Often mistaken for insect bites
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Complications
– Recurrent painful outbreaks
– Infections in babies can be fatal
– Increases HIV susceptibility
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Diagnosis
– Visual inspection
– Blood test to detect antibodies
– Lab test of sore samples
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Treatment
– No cure but antiviral drugs can shorten and prevent outbreaks
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Prevention
– Control outbreaks to reduce risk of transmission
– Abstinence during outbreaks
– Condoms may help reduce transmission risk but may not entirely cover infected
areas
Genital Warts
• Overview
– Caused by Human Papillomavirus (HPV)
• About 100 strains, of which 30 are sexually transmitted
• High risk strains (about 10 of 30) can lead to abnormal pap smears
and cause cancer of the cervix, vulva, vagina, anus, or penis
• Low risk types may cause mild Pap test abnormalities or genital
warts. Genital warts are single or multiple growths or bumps that
appear in the genital area, and sometimes are cauliflower shaped.
• Prevalence
– At least 50 percent of sexually active men and women acquire
genital HPV infection at some point in their lives
– By age 50, at least 80 percent of women will have acquired
genital HPV infection
– Most people will be asymptomatic and fight off infection on their
own
Genital Warts
• Diagnosis
– Visual inspection
– Often appear within weeks or months of contact, or not at all
– Usually appear as soft, moist, pink, or flesh-colored swellings, usually in
the genital area. They can be raised or flat, single or multiple, small or
large, and sometimes cauliflower shaped.
• Treatment
– No cure, but they will often go away on their own
– Regular pap smears can help detect pre-cancerous conditions for early
treatment
• Complications
– Can cause cervical cancer
• Prevention
– Abstinence, particularly during outbreaks
– Effectiveness of condoms against HPV is unknown but condom use has
been associated with a somewhat lower incidence of cervical cancer
Current Research and STD
Prevention Programs
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Debate between safer sex an abstinence programs.
– Research has tended to focus on one-time abstinence programs with no followup.
– Both approaches appear to work in the short term but SS programs tend to have
longer term effects among sexually active teens
• Abstinence and safer sex among adolescents.
Author: Masdeu JC Source: JAMA (JAMA : the journal of the American Medical
Association.) 1999 Apr 28; 281(16): 1486-8 Libraries Worldwide: 3891
• Abstinence and safer sex HIV risk-reduction interventions for African American
adolescents: a randomized controlled trial.
Author: Jemmott JB 3rd; Jemmott LS; Fong GT Source: JAMA (JAMA : the journal of
the American Medical Association.) 1998 May 20; 279(19): 1529-36
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Haglund K found that African American’s description of abstinence only
tended to include intercourse
– Still at risk for STDs
– Sexually abstinent African American adolescent females' descriptions of
abstinence.
Author: Haglund K Source: J Nurs Scholarsh (Journal of nursing scholarship :
an official publication of Sigma Theta Tau International Honor Society of Nursing /
Sigma Theta Tau.) 2003; 35(3): 231-6