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STD Epidemiology Jonathan Zenilman, MD Johns Hopkins University
Jonathan Zenilman, MD For the CDC he conceived, developed, and implemented the National Gonococcal Isolates Surveillance Program and wrote the 1989 STD Treatment Guidelines At Hopkins sine 1989, where he has developed an active clinical and translational research program focusing on STD epidemiology Chief of clinical services at the Baltimore City Health Department between 1992 and 1995 and senior medical advisor at the U.S. Department of Health and Human Services from 1995 to 1997 3
Section A Background
Importance of Preventing and Controlling STDs International health objective High rates of complications and adverse health outcomes High human and economic costs STDs facilitate the transmission of HIV (Wasserheit, 1992) Relationship to other co-morbidities such as substance use and mental illness 5
Events/Outcomes: Costs and Morbidity of Sexual Behavior Unintended pregnancy LBW infants Terminations STD direct costs-medical (PID) Long-term STD costs (ectopics, infertility) Emotional and economic costs Potentiated HIV Risk (3 6X) 6
Long After Kinsey, Only the Brave Study Sex 7
Condom Use at Last Sex (YRBS*) 1991 2001 *Youth Risk Behavior Surveillance System 8
Condom Use at Last Sex (GSS *) Data Source: Anderson et al. (2003, October 1). J Acquir Immune Defic Syndr, 34, 2, 195 202. *General Social Survey 9
Disease Rates Total Population Based Rate = Total cases of disease Total population Sexually active adults at risk for GC 10
Disease Rates Total Population Based Rate = Total cases of disease Total population 11
STI Incidence Factors INDIVIDUAL BEHAVIOR STI INCIDENCE BIOLOGY OF ORGANISM Inspired by Anne Johnson. (2005) 12
STI Incidence Factors BEHAVIOR OF POPULATIONS SES and Demographics CONTROL PROGRAMS STI INCIDENCE ECOLOGY ORGANISM TIME Inspired by Anne Johnson. (2005) 13
Structural Difference between Two Social Networks 14
Sexual Contacts among Homosexual Men with AIDS 15
Section B Bacterial STDs and the Epidemiological Applications
Gonorrhea Rates United States, 1970 2004, and the Healthy People 2010 target Note: The Healthy People 2010 target for gonorrhea is 19.0 cases per 100,000 population. Source: CDC Division of STD Prevention 17
Gonorrhea Rates by Race and Ethnicity United States, 1981 2002, and the Healthy People 2010 objective Rate (per 100,000 population) 2,500 2,000 1,500 White Black Hispanic Asian/Pac Isl Am Ind/AK Nat 2010 Objective 1,000 500 0 1981 83 85 87 89 91 93 95 97 99 2001 Source: CDC Division of STD Prevention 18
Gonorrhea Rates by County: United States, 2002 Note: The Healthy People 2010 objective for gonorrhea is 19.0 cases per 100,000 population Source: CDC Division of STD Prevention 19
Reported Gonorrhea Rates by Year: 1995 2004 Reported Gonorrhea Rates by Year: 1995-2004 (Projection) Health Promotion and Disease Prevention Baltimore City Health Department 1200.0 1000.0 Rate per 100,000 800.0 600.0 400.0 Baltimore US 200.0 0.0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004* Source: Baltimore City Health Department, STD Surveillance Unit July 2004 * Projected 2004 Rate 2003 and 2004 US Rates 20
Gonorrhea in Baltimore, 2003, by Gender and Location Baltimore City Health Dept. STD Suveillance Unit 21
Gonorrhea Rate per 100,000 per Census Block Group Gonorrhea rate per 100,000 per census block group, 1994 1999, Baltimore City Baltimore City Health Dept. STD Suveillance Unit 22
Chlamydia Rates by Sex: United States, 1984 2002 Rate (per 100,000 population) 500 400 300 200 Men Women 100 0 1984 86 88 90 92 94 96 98 2000 02 Source: CDC Division of STD Prevention 23
Section C Prevalent Chronic Viral Infections: Herpes Simplex
Prevalent Infections: The Control Challenge Strategy based on prevalent data Time trajectory often not known Evaluation of interventions is methodologically difficult Use of surrogate (e.g., behavioral) markers for evaluation 25
HSV-2 Seroprevalence: 1976 80 and 1988 94 (U.S.) 26
HSV-2 Seroprevalence By age, race/ethnicity NHANES III (1991) 27
HSV-2 Seroprevalence in the United States Source: Fleming, P. (1997). N Engl J Med; CDC National Meeting. (2004). 28
Subclinical Viral Shedding More than 90% of persons with genital HSV-2 shed virus asymptomatically Present 1 10% of asymptomatic days in persons who have recurrent herpes due to HSV-2 Uncommon in HSV-1 genital infection Frequency highest in first year after acquisition Responsible for most transmission Wald A NEJM 1995. 29
Section D Epidemiology of Syphilis
Primary and Secondary Syphilis Rates: 1995 2004 100.0 Reported Primary and Secondary Syphilis rates by Year: 1995-2004 (Projection) Health Promotion and Disease Prevention Baltimore City Health Department 90.0 80.0 70.0 Rate per 100,000 60.0 50.0 40.0 Baltimore US 30.0 20.0 10.0 0.0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004* Source: Baltimore City Health Department, STD Surveillance Unit July 2004 * Projected 2004 Rate 2003 and 2004 US Rates Baltimore City Health Dept. STD Suveillance Unit 31
Primary and Secondary Syphilis Rates, United States Primary and Secondary Syphilis Rates, United States, 1970 2004, and the Healthy People 2010 target Rate (per 100,000 population) 25 20 P&S Syphilis 2010 Target 15 10 5 0 1970 73 76 79 82 85 88 91 94 97 2000 03 Note: The Healthy People 2010 target for P&S syphilis is 0.2 case per 100,000 population. Source: CDC Division of STD Prevention 32
Syphilis Epidemiology Reflects Social Trends 1940s 1970s Poverty in the South and minority communities; CSWs 1975 1981 Gay liberation movement 1981 1989 AIDS epidemic 1988 1995 Crack cocaine epidemic 1997 2005 Syphilis elimination campaign Resurgence in homosexual men 33
Baltimore City Reported Early Syphilis, 2003 34
Male-to-Female Ratio, 2004 Source: CDC Division of STD Prevention 35
Section E Reproductive Rate Equation
Simple but Useful Equation R o = ß c D Reproductive rate Probability of transmission Number of sexual contacts Duration of infectiousness Source: Anderson and May. (1992). 37
Duration of Infection Interventions R o = ßcD Duration of infection interventions Reduction of d = reduction of asymptomatic pool Disease screening programs Partner notification and presumptive treatment Increased health care access Treatment guidelines 38
Transmission Efficiency Interventions R = ßcd Transmission efficiency interventions Condom use and barrier methods Microbicides Hormonal contraceptives(?) Circumcision(?) Antiviral therapy(?) Doc, now that my viral load is zero, do I still have to use a condom? Can I get a prescription for Viagra? 39
Section F HIV-STD Interactions
STDs As Cofactors in HIV Transmission STDs increase HIV transmission may influence HIV replication viral load in genital secretions (ex: HSV-2 associated with higher HIV levels in plasma and in genital secretions) STDs increase susceptibility to HIV Disrupt mucosal barrier number of receptor cells in genital tract receptors expressed per cell 41
Importance of Acute HIV Infection in Transmissibility 42
Increased STDs in Gay Men Trend observed since 1999 Behavioral relapse and increased disease rates High proportion HIV-positive in syphilis epidemics Trend observed in U.S. and Western Europe 43