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Curable versus incurable STDs

Curable versus incurable STDs

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Curable versus incurable STDs

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  1. Curable versus incurable STDs

  2. Objectives • To describe the natural history and epidemiology of two curable STDs (i.e. syphilis and chlamydia) and two non-curable STDs (i.e. Herpes and HPV) • To discuss study design issues specific to curable versus non-curable diseases

  3. Natural history of a curable disease Symptoms diagnosis cure Infection Testing treatment Prevalence = ∑ (incidence – cured)

  4. Things that contribute to non-treatment among curable STDs • Lack of index treatment • Failure to return for treatment • Non-adherence to medication • Given incorrect medicine • Lack of partner treatment • Treatment failure

  5. Natural history of a non-curable disease Symptoms diagnosis Infection Testing Prevalence = ∑ incidence

  6. Non-curable STDs(e.g. HIV, Herpes, HPV) • Long infectious period • Few population based screening programs • No curative treatments • Incidence may be very different than prevalence

  7. Treponema pallidum (syphilis)

  8. Issues in syphilis • Test doesn’t tell if it is incident and won’t pick up tertiary • Symptoms change depending on staging • Most at risk, least likely to get tested and treated

  9. Syphilis - curable • Caused by Treponema pallidum • primary lesion usually occurs 3 weeks after exposure • secondary manifestations occur weeks to 12 months after initial exposure • tertiary • treatment is parenteral penicillin G

  10. Progression of syphilis

  11. Staging of Syphilis

  12. Testing and symptoms

  13. Male chancres

  14. Chancre in a female

  15. Late stage manifestations of syphilis

  16. ChlamydiaSexually Transmitted Disease Surveillance 2001 Division of STD Prevention

  17. Chlamydia — Number of states that require reporting of Chlamydia trachomatis infections: United States, 1987–2001

  18. Chlamydia — Reported rates: United States, 1984–2001

  19. Chlamydia — Rates by state: United States and outlying areas, 2001 Note: The total rate of chlamydia for the United States and outlying areas (including Guam, Puerto Rico and Virgin Islands) was 275.5 per 100,000 population.

  20. Chlamydia — Rates by region: United States, 1984–2001

  21. Chlamydia — Rates by sex: United States, 1984–2001

  22. Chlamydia — Age- and sex-specific rates: United States, 2001

  23. Chlamydia — Positivity among 15-24 year old women tested in family planning clinics by state: United States and outlying areas, 2001 Note: States reported chlamydia positivity data on at least 500 women aged 15-24 years screened during 2001. SOURCE: Regional Infertility Prevention Program; Office of Population Affairs; Local and State STD Control Programs; Centers for Disease Control and Prevention

  24. Tests Culture antigen detection (indirect) nucleic acid amplification (direct)

  25. Herpes

  26. Issues for Herpes • Variable presentation • Stigma and reporting bias • Non-treatable • Prevalence increases with age

  27. Herpes Simplex -2 • One of most common, 1 million incident and 45 million prevalent in U.S. per year. • Less than 10% of those infected are aware. • Greek term meaning “to creep or crawl” • Acquired sexually • HSV-1 (oral herpes) can cause 30-40% of genital herpes • Tested using an antibody test • Increasing age, low SES, more partners, women and African Americans at higher risk

  28. HSV-2 • More than 20% of Americans are infected • From 70s to 90s prevalence increased 30% • NHANES suggests it leveled off in 1990s except for white teenagers. • Treated with acyclovir, famciclovir, valaciclovir, foscarnet, cidofovir gel, trifluridine and interferon • an effective therapeutic vaccine for genital herpes has not been successful to date, although a live virus glycoprotein H-deficient (DISC) vaccine is currently in clinical trials

  29. Genital herpes — Initial visits to physicians’ offices: United States, 1966–2001 SOURCE: National Disease and Therapeutic Index (IMS America, Ltd.)

  30. Genital herpes simplex virus type 2 infections — Percent seroprevalence according to age in NHANES* II (1976-1980) and NHANES III (1988-1994) Note: Bars indicate 95% confidence intervals. *National Health and Nutrition Examination Survey

  31. Complicated Scenarios • How to measure incidence of HIV? • How to study the efficacy of a vaccine for Herpes? • How to study the efficacy of treatment for HPV?