Session 8Oral Abstract Presentations Epidemiology Session Day and Time: Tuesday 10 am - 12:15 pm Presentation Time: 11:00 Room: 302-306
40 HIV-1 Transmission per Coital Act, by Stage of HIV Infection in the HIV+ Index Partner, in Discordant Couples, Rakai, Uganda M. J. Wawer*1, D. Serwadda2, X. Li3, T. C. Quinn3, N. K. Sewankambo2, N. Kiwanuka4, G. Kigozi4, R. H. Gray3 1Columbia Univ, New York, NY; 2Makerere Univ, Kampala, Uganda; 3Johns Hopkins Univ, Baltimore, MD; and 4Rakai Project, Entebbe, Uganda
Objective: To determine the rates of HIV-1 transmission per coital act in discordant couples in rural Rakai District, Uganda, by the stage of HIV infection in the index HIV+ partner.
Methods: A total 240 HIV discordant couples (217 with HIV prevalent index partners and 23 with HIV incident index partners) in which the HIV-uninfected partner was monogamous, were retrospectively identified within a population-based cohort. The cohort was followed at 10-monthly intervals between 1995 and 1999. Information on coital frequency was collected at each 10-monthly survey. The rate of HIV transmission per coital act, stratified by the characteristics, symptoms and HIV viral load of the index infected partner, was assessed by the stage of infection in the index partner. Stage was defined as recent (incident) HIV infection, prevalent infection, and the period prior to death.
Results: Seventy-two (72) of the 240 (30%) of the index HIV-infected persons transmitted to their partners. The rate of HIV transmission per coital act was highest in the 5-month (mo) period following index seroconversion (0.0081/ coital act), declined to 0.0016/coital act at 5-15 mos after index seroconversion, stabilized at 0.0010 per act among HIV prevalent index partners, and increased prior to index partner death (0.0029/act at 15125 months before death, and 0.0043/act at 5115 months prior to death). Symptoms in the HIV+ index partner were not significantly associated with transmission at any stage. Index partner HIV viral load was the strongest predictor of transmission at each stage of infection.
Conclusions: HIV transmission per coital act was elevated following seroconversion, declined rapidly and remained stable during latency, and increased in the 2 yrs prior to death. Approximately half of all HIV transmission within Rakai discordant couples was estimated to occur within 5 mos of index partner seroconversion. This has implications for HIV prevention programs, since recently infected persons are less likely to know their status and to have received counseling or other interventions.
