AEGiS-14IAC: Effects of population characteristics on the impact of STD/HIV control strategies: model predictions in a range of populations.

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

Effects of population characteristics on the impact of STD/HIV control strategies: model predictions in a range of populations.

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no. MoOrD1087)

White RG, Orroth KK, Korenromp EL, Bakker R, Wambura M, Serwadda D, Whitworth JA, Gray RH, Grosskurth H, Habbema JD, Hayes RJ
London School of Hygiene and Tropical Medicine, London, United Kingdom

BACKGROUND: Population differences have provided an explanation for the differential impact observed in the Mwanza, Rakai and Masaka STD/HIV intervention trials. We explore the impact of the 4 HIV prevention strategies in a range of populations.

METHODS: The STDSIM microsimulation model was used to simulate the transmission of gonorrhoea, chlamydia, chancroid, syphilis, trichomoniasis, HSV2 and HIV in the 3 trial populations. STD natural history, cofactor values, transmission probabilities, and the demography, sexual behaviour and HIV/STD epidemiology of the trial populations were based on trial data and literature review. In each site, 5 scenarios were run (100 iterations) representing: no intervention; sustained syndromic treatment; 3 rounds of mass treatment; IEC (not shown); IEC + sustained syndromic treatment (not shown).

RESULTS: A good fit of the model to baseline data on demography, sexual behaviour and HIV/STD epidemiology was achieved (not shown). The substantial predicted impact of mass and syndromic STD treatment on STD prevalence (gonorrhoea illustrated) in all sites contrasts with the relatively small predicted impact on HIV incidence in Rakai and Masaka compared to Mwanza (table). [table: see text] Table. Projected cumulative 2 year HIV incidence reduction and gonorrhoea prevalence reduction after 2 years (%, 15-54y).

CONCLUSIONS: Population differences and prevention strategy will co-determine the impact of STD/ HIV prevention activities. The population impact of STD management varies with curable STD prevalence. This study supports the hypothesis that STD management is an effective HIV prevention strategy in populations with a high prevalence of curable STD and an expanding HIV epidemic. These are preliminary results, final results, including model outputs for the Masaka trial, and the projected impact in other populations will be presented.

Keywords: AEGIS, HIV Infections, Prevalence, Incidence, Sex Behavior, Acquired Immunodeficiency Syndrome, HIV Seropositivity, Gonorrhea, Syphilis, Chlamydia Infections, Demography, Greece

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MoOrD1087