Rates of HIV-1 Transmission per Coital Act, by Stage of HIV-1 Infection, in Rakai, Uganda

• Published in: The Journal of infectious diseases Vol. 191; no. 9; pp. 1403 - 1409
• Main Authors: Wawer, Maria J., Gray, Ronald H., Sewankambo, Nelson K., Serwadda, David, Li, Xianbin, Laeyendecker, Oliver, Kiwanuka, Noah, Kigozi, Godfrey, Kiddugavu, Mohammed, Lutalo, Thomas, Nalugoda, Fred, Wabwire-Mangen, Fred, Meehan, Mary P., Quinn, Thomas C.
• Format: Journal Article
• Language: English
• Published: United States The University of Chicago Press 01.05.2005; Oxford University Press
• Subjects: Acquired Immunodeficiency Syndrome - epidemiology; Acquired Immunodeficiency Syndrome - pathology; Acquired Immunodeficiency Syndrome - transmission; Adolescent; Adult; Coitus; Female; HIV-1 - isolation & purification; Humans; Incidence; Male; Poisson Distribution; Sexually Transmitted Diseases - transmission; Sexually Transmitted Diseases - virology; Time Factors; Uganda - epidemiology; Viral Load; Uganda
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1086/429411

BackgroundWe estimated rates of human immunodeficiency virus (HIV)–1 transmission per coital act in HIV-discordant couples by stage of infection in the index partner MethodsWe retrospectively identified 235 monogamous, HIV-discordant couples in a Ugandan population-based cohort. HIV transmission within pairs was confirmed by sequence analysis. Rates of transmission per coital act were estimated by the index partner’s stage of infection (recent seroconversion or prevalent or late-stage infection). The adjusted rate ratio of transmission per coital act was estimated by multivariate Poisson regression ResultsThe average rate of HIV transmission was 0.0082/coital act (95% confidence interval [CI], 0.0039–0.0150) within ∼2.5 months after seroconversion of the index partner; 0.0015/coital act within 6–15 months after seroconversion of the index partner (95% CI, 0.0002–0.0055); 0.0007/coital act (95% CI, 0.0005–0.0010) among HIV-prevalent index partners; and 0.0028/coital act (95% CI, 0.0015–0.0041) 6–25 months before the death of the index partner. In adjusted models, early- and late-stage infection, higher HIV load, genital ulcer disease, and younger age of the index partner were significantly associated with higher rates of transmission ConclusionsThe rate of HIV transmission per coital act was highest during early-stage infection. This has implications for HIV prevention and for projecting the effects of antiretroviral treatment on HIV transmission