Curable versus incurable STDs

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

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

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

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

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

Treponema pallidum (syphilis)

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

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

Progression of syphilis

Staging of Syphilis

Testing and symptoms

Male chancres

Chancre in a female

Late stage manifestations of syphilis

Chlamydia Sexually Transmitted Disease Surveillance 2001 Division of STD Prevention

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

Chlamydia — Reported rates: United States, 1984–2001

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 per 100,000 population.

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

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

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

Chlamydia — Positivity among 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 years screened during SOURCE: Regional Infertility Prevention Program; Office of Population Affairs; Local and State STD Control Programs; Centers for Disease Control and Prevention

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

Herpes

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

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

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

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

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

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?