Determinants of Per-Coital-Act HIV-1 Infectivity Among African HIV-1-Serodiscordant Couples

• Published in: The Journal of infectious diseases Vol. 205; no. 3; pp. 358 - 365
• Main Authors: Hughes, James P., Baeten, Jared M., Lingappa, Jairam R., Mageret, Amalia S., Wald, Anna, de Bruyn, Guy, Kiarie, James, Inambao, Mubiana, Kilembe, William, Farquhar, Carey, Celum, Connie
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.02.2012
• Series: Editor's Choice
• Subjects: Adult; Africa; Biological and medical sciences; Condoms; Condoms - utilization; Disease transmission; Family Characteristics; Female; Fundamental and applied biological sciences. Psychology; Genotype; Herpes simplex virus 2; HIV; HIV 1; HIV Infections - transmission; HIV Infections - virology; HIV-1 - classification; HIV-1 - genetics; HIV-1 - isolation & purification; HIV/AIDS; Human herpesvirus 2; Human immunodeficiency virus 1; Humans; Infections; Infectious diseases; Major and Brief Reports; Male; Medical sciences; Microbiology; Miscellaneous; Prospective Studies; Research universities; Risk Assessment; RNA; RNA, Viral - genetics; Sexual Behavior - statistics & numerical data; Sexual transmission; Trichomonas vaginalis; Vaginitis; Viral Load; Virology; Africa; Virus; Infection; HIV-1 virus; Infectivity; Retroviridae; Human immunodeficiency virus; Lentivirus
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1093/infdis/jir747

Background. Knowledge of factors that affect per-act infectivity of human immunodeficiency virus type 1 (HIV-1) is important for designing HIV-1 prevention interventions and for the mathematical modeling of the spread of HIV-1. Methods. We analyzed data from a prospective study of African HIV-1-serodiscordant couples. We assessed transmissions for linkage within the study partnership, based on HIV-1 sequencing. The primary exposure measure was the HIV-1-seropositive partners' reports of number of sex acts and condom use with their study partner. Results. Of 3297 couples experiencing 86 linked HIV-1 transmissions, the unadjusted per-act risks of unprotected male-to-female (MTF) and female-to-male (FTM) transmission were 0.0019 (95% confidence interval [CI], .0010-.0037) and 0.0010 (95% CI, .00060-.0017), respectively. After adjusting for plasma HIV-1 RNA of the HIV-1-infected partner and herpes simplex virus type 2 serostatus and age of the HIV-1-uninfected partner, we calculated the relative risk (RR) for MTF versus FTM transmission to be 1.03 (P = .93). Each log₁₀ increase in plasma HIV-1 RNA increased the per-act risk of transmission by 2.9-fold (95% CI, 2.2-3.8). Self-reported condom use reduced the per-act risk by 78% (RR = 0.22 [95% CI, .11-.42]). Conclusions. Modifiable risk factors for HIV-1 transmission were plasma HIV-1 RNA level and condom use, and, in HIV-1-uninfected partners, herpes simplex virus 2 infection, genital ulcers, Trichomonas vaginalis, vaginitis or cervicitis, and male circumcision.