Class 7- STI Flashcards
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Clinical syndromes of Hepatitis <!--EndFragment--><!--EndFragment-->
All hepatitis viruses cause the same general syndrome.
- Inflammation of the liver
- Hallmark of hepatitis is elevation of liver enzymes (ALT & AST) or presentation with jaundice
Types of Hepatitis
- Hepatitis A Virus (HAV) – fecal oral
- Hepatitis B Virus (HBV) – blood borne
- Hepatitis C Virus (HCV) – blood borne/sexually transmitted
- Hepatitis D Virus (HDV) – requires HBV infection to occur, deadly
- Hepatitis E Virus (HEV) – fecal oral
Hepatitis Incubation Periods
Variations in incubation by virus
- HAV & HEV – 2 to 10 weeks
- HCV – 4 to 10 weeks
- HBV – 6 to 20 weeks
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Hepatitis A distribution<!--EndFragment-->
Low socioeconomic status associated with high rates of infection in the US
- Hot spots of transmission -American Indians and Hispanic residents
- In countries with high endemicity of HAV, most cases occur in children under 15 yrs
7 to 10 year peaks in the number of reported cases in the US (Think SEIR models*)
- Low transmission results in accumulation of large susceptible population- risk for major outbreak
Hepatitis A
Stable in the environment after it is shed in feces
- Retains infectivity 2 to 4 weeks at room temperature
- Resistant to free chlorines and other detergents
- Explains outbreaks associated with pools
Transmission through consumption of contaminated food or water, or direct person to person
- Bloodborn transmission is uncommon
Risk of HAV infection during international travel to developing countries is highest among long-term residents
- Longer potential exposure
- Difficulty in procuring clean water and food for prolonged periods
Prevention
- Improved environmental sanitation and personal hygiene
- Vaccine preventable
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Hepatitis B virus<!--EndFragment-->
Closely linked with primary hepatocellular carcinoma (liver cancer)
- WHO estimates 80% of all cases of PHC occur in persons with chronic HBV infection
Transmitted by:
- Percutaneous blood exposure, sexual transmission, and Vertical Transmission (mother to infant)
- Risk of transfusion transmission has decreased substantially following HBsAg screening and excluding high-risk populations for HBV, HCV, and HIV
Vaccine preventable
- Treatment can suppress replication of virus but does not eradicate infection
HBV-HIV coinfection is very common
- 40 million persons with HIV
- 400 million are chronic HBV carriers
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Hepatitis C virus<!--EndFragment-->
Infections are often persistent
- Indicates viral evolution to escape immune response
Acute HCV infection is usually unnoticed
- Fewer than 20% will have jaundice
- After acute infection – 60 to 85% will have persistent viremia lasting 10 to 50 years with or without symptoms
2 to 25% of individuals with persistent HCV will develop life-threatening cirrhosis and/or liver cancer
10,000 persons die of HCV each year in the US
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Needle-stick and nosocomial transmission<!--EndFragment-->
With a single needle-stick exposure
- 1% to 3% risk of HCV
- 30% risk of HBV
- 0.3 % risk of HIV
Because of needle-stick exposure 50-95% of persons with history of illicit drug use have HCV infections
HCV is also transmissible through sexual contact but the primary transmission method is needle injection
Importance of needle exchange programs
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HCV globally (2011)<!--EndFragment-->
Estimated 170 million persons infected with HCV
No data in western Europe? High levels of injection drug use…
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Hepatitis D virus<!--EndFragment-->
Relies on components of HBV virus to cause infection
- Thus only occurs in HBV co-infected individuals
2-20% mortality rate (10 times higher than HBV mortality rate)
Transmission occurs though parenteral exposure to blood and sexual contact with a carrier.
- Outbreaks reported among injection-drug users in Los Angeles and Worcester MA.
- Uncommon in China and South East Asia, despite high levels of HBV endemicity.
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Hepatitis E virus <!--EndFragment-->
One of the most frequent causes of viral hepatitis globally
- Individuals usually recover from infection
Associated with large scale outbreaks in developing countries
Gaining more attention in scientific communities
The difference is between STD and STI?
STD disease carries the implication of distinct clinical symptoms
STI has a broader scope, including those who are asymptomatic
Trend towards calling these infections STIs over STDS
- Less stigma
- Hints at underlying non-reported infections
- Basically the same thing
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Key sexually transmitted infections <!--EndFragment-->
- Bacterial vaginosis – bacteria
- Chancroid - bacteri
- Chlamydia – bacteria
- Genital Herpes –virus
- Gonorrhea – bacteria
- Hepatitis viruses
- HIV- viral
- HPV – virus
- Pediculosis – parasite
- Scabies – parasite
- Syphlis – bacteria
- Trichomonas – parasite
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STI Risk factors
- Gender
- Sexual behaviors
- Route of exposure – oral, vaginal, anal
- Receptive rectal intercourse and vaginal intercourse carry the highest risks of STD transmission
- Number of partners
- Condom use practices
- Auto immune diseases
- Uncircumcised
- Co-infections
- Injection drug use
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Chlamydia- Chlamydia trachomas (serovars D-K)
Reservoir- Humans
Route- sexual intercourse, neonatal infections occur from exposure to mother’s infected cervix
Incubation – poorly defined 7-14 days
Symptoms – manifest in males as urethritis, females cervical infection, burning urination, and slight discharge. Asymptomatic infection estimated to occur in 1 to 25% of sexually active men.
Communicability- unknown
What do Chlamydia trachomas serovars A-C cause? (A-C are not sexually transmitted)
- Drachomas
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Chlamydia Gender differences
Men
- Chlamydia accounts for approximately 40% of nongonoccoal urethritis in the US
- Presents as a mucoid discharge
- Asymptomatic infection occurs in more than 30% of cases.
Women
- Bear the burden of most of the morbidity due to chlamydia infections because of the seriousness of sequelae of infections specifically pelvic inflammatory disease (PID)
- Cervical infection is the most commonly reported syndrome
- More than half of cases are asymptomatic
- Left untreated 30% will develop PID
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Chlamydia Epidemiology<!--EndFragment-->
Prevalence:
- 610/100,000 women and 233/100,000 men.
- OBGYN physical examinations are likely responsible for increased reporting in women.
- True estimates of chlamydia prevalence are hard to ascertain
Rates begin to drop off as women age
- Not related solely to behavior but may also reflect partial immunity
Gonorrhea- Neisseria gonorrhoeae Disease Profile
Reservoir- strictly a human disease
Route- almost always a result of sexual activity
- Is an indicator of child abuse in children over the age of 1
Incubation – usually 2-7 days can be longer
Symptoms – Urethritis discharge or dysuria usually appears within one week of exposure, although 5-10% never have signs or symptoms. Oral gonorrhea presents as painful sores and blisters of the lips, tongue and throat.
Communicability- may extend months in untreated individuals, effective treatment ends communicability within hours.
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Gonorrhea Gender differences
Men
- Urethritis and dysuria
- In homosexual men
- Anorectal gonococcal disease occurs in persons with a history of receptive rectal intercourse
- Symptoms of rectal pain, constipation, and discharge
- Anorectal gonococcal disease occurs in persons with a history of receptive rectal intercourse
Women
- Gonococcal cervicitis which if untreated can lead to PID
- Anorectal disease can also occur in women who have endocervical gonorrhea and who have not necessarily had receptive rectal intercourse
- Infection is presumed to have occurred via secretion across the perineum
- As many as 30% of women with endocervical gonorrhea have coexistent rectal infection.
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Gonorrhea Epidemiology<!--EndFragment-->
Gonorrhea is one of the oldest diseases known to humans
- Gonorrhea in Greek means “flow of seed”
- Was described in the old testament, ancient Chinese texts, and Egyptian writings
309,341 cases of gonorrhea were reported in the US
Problem with surveillance is it relies on passive detection
- Difference between incidence and asymptomatic prevalence
Highest rates seen in adolescent women age 15-19 years and young adult men 20-24 years.
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Pelvic Inflammatory Disease<!--EndFragment-->
Causes:
- Often considered to be a result of gonorrhea, chlamydia, enteric organisms and anaerobic organisms
- Poorly defined syndrome in part because it affects multiple organs
Overall direct economic impact of PID has been estimated to be 4.2 billion
Westrom Sweedish Cohort:
- Found 10% of women with one episode of PID had tubal infertility
- 25% with two episodes had tubal infertility
- More than 60% of women with three episodes had tubal infertility
- 10 x higher risk of ectopic pregnancy
PID epidemiology and factors that increase
An estimated 500,000 to 1,000,000 cases of PID annually
Difficult to accurately predict as PID syndrome is not a reportable disease
PID is associated with adolescence, increased number of partners, previous episodes of PID, use of an IUD, and douching
Primary prevention reducing gonococcal and chlamydial infection appears to be the most effective approach.
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Syphilis- Treponema pallidum<!--EndFragment-->
Reservoir- humans
Route- exposure almost always occurs through oral, vaginal and anal sexual intercourse in adults, transplacental transmission
Incubation – 10 days to three months
Symptoms
- Early- small, painless ulcers on genitals or mouth
- Secondary stage- rosy “copper penny” rash typically on the palms of the hands and soles of the feet
- Latent stage- infection lies dormant without showing symptoms
- Tertiary stage- If the infection isn’t treated, it may then progress to a stage characterized by severe problems with the heart, brain, and nerves that can result in paralysis, blindness, dementia, deafness, impotence, and even death if it’s not treated.
Communicability- exists when moist mucocutaneous leisons of primary and secondary syphilis are present
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Syphilis- High risk groups, transmission rate and notification<!--EndFragment-->
Symptoms are similar between Men and Women
All stages of syphilis are seen more commonly in HIV infected patients
Occurs in settings with high turnover of sexual partners
Linked with bath houses and homosexual activity
Increased rates in MSM population
- Risky sexual behaviors
- “Safe-sex fatigue” in HIV infected men
Transmission of syphilis is relatively ineffective
- 20% transmission efficiency between an infected partner and uninfected partner
Was the prototype disease for partner notification strategies
- Presumptive treatment with penicillin of partners of infected persons
- Still effective treatment today after 50 years of use.
Historical figures with syphilis
- Napoleon
- Ivan the terrible
- Adolf Hitler (suspected)
- Al Capone
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Clinical stages of syphilis<!--EndFragment-->
- Primary
- A chancre develops at the site of contact
- Systemic disease occurs in 10-15% of patients with primary stage, found in cerebrospinal fluid
- Secondary
- Four to eight weeks later secondary syphilis develops
- Development of lesions, patchy alopecia (especially around the scalp), and large fleshy wart-like lesions
- Tertiary and Latent syphilis
- Do not develop until 10-20 years after the resolution of early syphilis
- Causes neurosyphyilis, cardiovascular syphilis, and gummatous syphilis.
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Genital Herpes- herpes simplex virus (HSV) <!--EndFragment-->
Reservoir- Humans
Route- contact with HSV-1 in the saliva of carriers. Transmission of HSV-2 is usually by sexual contact
Incubation – 2-12 days
Symptoms – viral infection with local symptoms, latency, and tendency to recur. Present as genital lesions and stomatitis
Communicability- 2 weeks – 7 weeks after primary infection, usually only 5 days after recurrent infection
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HSV type 1 and type 2<!--EndFragment-->
- Problem in differentiating between recurrences versus new infection, difficult to ascertain accurate incidence data.
- HSV-1
- Usually causes orofacial herpes (cold sores), can occur on genitalia
- HSV-2
- Responsible for the bulk of genital infections, can occur orally
- There is a shift of genital herpes from HSV-2 to HSV-1
- Two hypotheses
- Increased oral sexual behavior
- Lack of prior exposure as children to oral herpes, leading to increased susceptibility
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Herpes epidemiology<!--EndFragment-->
1 in 6 married sexually active Americans is infected with herpes simplex virus
- Most of these individuals are asymptomatic
Worldwide, 50%-90% of adults have antibodies to HSV-1
HSV-2 antibodies occur in 20-30% of American adults
HSV-2 is an indicator of sexual abuse in children
Approximately 90% of genital herpes is caused by HSV-2
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Herpes simplex in pregnancy <!--EndFragment-->
Is not a severe clinical problem unless lesions are present
Major concern is to prevent transmission during pregnancy
- Cesarean section to prevent transmission if HSV active infection is occurring
- Developing primary herpes in the third trimester can lead to neonatal herpes syndrome which may be fatal or lead to disability
- Roughly 1,500 cases of newborn herpes occur annually in the United States
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Chancroid- haemophilus ducreyi<!--EndFragment-->
Reservoir- humans
Route- direct sexual contact with discharges from open lesions and pus from buboes. Auto-inoculation to non-genital sites may occur in infected persons
Incubation – 3-5 days up to 14 days
Symptoms – painful necrotic ulcers that bleed on contact. More frequently found in uncircumcised men on the foreskin.
Communicability- until healing of the primary leisions
Factors that increase risk of Chancroid
Chancroid ulcers like other genital ulcers are associated with an increased risk of HIV infection.
Most common genital ulcer disease in developing parts of the world
Prevalent in tropical and subtropical regions where incidence may be higher than syphilis. Diagnosised in men more often than women, especially clients of sex workers
Outbreaks in the US are rare and principally occur among migrant workers and poor inner city residents who are clients of sex workers.
No homosexually related epidemics have been reported in the United States
Other risk factors include alcohol use, intravenous drug use, and contact with commercial sex workers.
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HPV Gender Differences
- HPV infections are extremely common in women, with incidence rates greater than 20% per year
- Reporting mechanisms can skew this number
- Highest risk period appears to be within the year after initiating sexual intercourse
- Nearly 100% of cervical cancers are suspected to be associated with HPV
- Development of early cervical cancer is often 5-10 years
- HPV in men causes 83-95% of anal cancers and 30-42% of penile cancers.
- Growing body of evidence has also linked HPV with oropharyngeal and neck cancer
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HPV and cervical cancer<!--EndFragment-->
The strength of association between High risk persistent HPV infection and invasive cervical cancer is an OR of 45:1.
- However when adjusted for the high prevalence of transient HPV infection among sexually active women and the frequent resolution of HPV associated lesions, the reality is HR-HPV is a necessary but insufficient cause of invasive cervical cancer
- Coupled with regular screening the risk of HPV cancer mortality drops significantly
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Vaginal infections<!--EndFragment-->
Trichomoniasis
- 7 – 8 million infections annually in the US, as many as 180 million globally
Represents the most curable STD in young sexually active women
- Does not produce systemic disease in host
- Has been associated with the potential facilitation of HIV infection
- Economic burden is 19 million a year in US women
Bacterial vaginosis
- Result of ecological disruption among the vaginal flora due to pH imbalances
- Clinical manifestation include vaginal odor and discharge
- Can result in premature rupture of membranes and premature delivery in pregnant women
Community level STI Prevention
- Sex ed
- Making condoms available
Individual Level STI Prevention
- Using condoms
- STI screenings
HPV vaccine
A vaccine has been developed and is 98-100% effective for types 6, 11, 16, and 18.
CDC recommends vaccine in females between the ages of 11-12 years
New push for boys to receive the vaccine as well
