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HIV Serosorting? Increases in Sexually Transmitted Diseases and Risk Behavior Without Concurrent Increases in HIV Incidence Among Men Who Have Sex With Men in San Francisco. Hong-Ha M. Truong, PhD, MS, MPH Center for AIDS Prevention Studies Gladstone Institute of Virology & Immunology
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HIV Serosorting?Increases in Sexually Transmitted Diseases and Risk Behavior WithoutConcurrent Increases in HIV Incidence Among Men Who Have Sex With Menin San Francisco Hong-Ha M. Truong, PhD, MS, MPH Center for AIDS Prevention Studies Gladstone Institute of Virology & Immunology University of California, San Francisco
MSM Communities • Men who have sex with men (MSM) during late 1990’s to early 2000’s had increasing rates of: • sexual risk behavior • sexually transmitted infections (STI) • HIV incidence • Trends observed worldwide • North America • Europe • Australia
MSM in San Francisco • MSM seeking HIV testing (1995 – 1999) • concurrent increases • sexual risk behavior • male rectal gonorrhea • HIV incidence • Late 1990’s to early 2000’s • Syphilis cases increased exponentially (1997-2002) • No concomitant increase in recent HIV infection • Change in HIV epidemic among MSM?
HIV Serosorting • HIV serosorting • selection of sexual partners by HIV serostatus • modifying sexual practices based on knowledge of • one’s own serostatus • serostatus of one’s partner • Increase in HIV serosorting may explain the paradoxical rise in STI transmission without a concurrent rise in HIV transmission
Study Design • Secondary analysis of multiple data sources • Second Generation HIV Surveillance (UNAIDS/WHO) • multiple data sources to strengthen interpretation • combines biological and behavioral measures • flexible to different phases of epidemic • focus on temporal trends and changes
Data Sources • STI surveillance • San Francisco Department of Public Health • STI registry: rectal gonorrhea and early syphilis • STOP AIDS Project • community-based organization • conducts serial cross-sectional surveys of MSM at gay-oriented venues • HIV testing programs • anonymous testing sites (ATS) • municipal STI clinic voluntary HIV testing (STI)
Sample Size * Second half of 1998 only
Age Age 40 and over at all sites (p<0.001)
Race/Ethnicity White at all sites (p<0.001) Asian-American at ATS & STI (p<0.001) Hispanic at STI (p<0.001) African-American at ATS (p<0.001) at STI (p=0.02) & SAP (p=0.002)
Early Syphilis & Rectal Gonorrhea Truong HM, et al. Sexually Transmitted Infections. in press
Unprotected Anal IntercourseSAP p<0.001 p<0.001 p<0.001 * Second half of 1998 only Truong HM, et al. Sexually Transmitted Infections. in press
UAI With Known HIV+ PartnerATS p<0.001 p<0.001 p<0.001 Truong HM, et al. Sexually Transmitted Infections. in press
UAI With Known HIV+ PartnerSTI p<0.001 p<0.001 p<0.001 Truong HM, et al. Sexually Transmitted Infections. in press
HIV Incidence Truong HM, et al. Sexually Transmitted Infections. in press
Summary • Syphilis and male rectal gonorrhea continued to rise even as HIV incidence leveled off • Behavioral data from SAP, ATS and STI support hypothesis that MSM are increasingly selecting HIV seroconcordant partners when engaging in UAI
Summary • SAP • any UAI: overall increase • UAI with partners of unknown HIV serostatus • declined among HIV-positives • declined among HIV-negatives • ATS and STI • UAI with known HIV+ partner • overall decrease • similar prevalence: 11.6% ATS, 11.0% STI
Discussion • Serosorting may prevent further increases in HIV transmission among MSM in San Francisco • HIV incidence remained at relative plateau through 2004 at two large testing programs • follows period of resurgent risk behavior, STI, and HIV incidence in late 1990’s • findings comparable to MSM studies in Sydney
Discussion • New phase of HIV epidemic? • Increases in HIV serosorting may prevent further expansion of epidemic • “Prevention for Positives” • initiation & intensification - late 1990’s/early 2000’s • prevent secondary transmission from persons who know they are HIV-positive • Internet • may facilitate partner selection by HIV serostatus • provides semi-anonymous environment for disclosure of sensitive information
Discussion • Vulnerabilities of such serosorting strategies • imperfect knowledge of one’s own HIV serostatus • uncertainty of partners’ HIV serostatus • transmission probabilities of certain sexual practices • Serosorting strategy may be more feasible in San Francisco than elsewhere • high level of HIV testing among MSM • 97% of MSM in San Francisco had ever tested • 34% had tested in the past 6 months
Acknowledgements Gladstone Institute of Virology & Immunology • Robert Grant Stop AIDS Project • Karl Knapper San Francisco Department of Public Health • Willi McFarland • Jeffrey Klausner • Mitchell Katz • James Dilley • Timothy Kellogg • Sanny Chen • Roop Prabhu • Brian Louie