Determinants of per-coital-act HIV-1 infectivity among African HIV-1–serodiscordant couples

JP Hughes, JM Baeten, JR Lingappa… - Journal of Infectious …, 2012 - academic.oup.com
JP Hughes, JM Baeten, JR Lingappa, AS Magaret, A Wald, G de Bruyn, J Kiarie, M Inambao…
Journal of Infectious Diseases, 2012academic.oup.com
Abstract (See the editorial commentary by Gray and Wawer on pages 351–2.) 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 …
Abstract
(See the editorial commentary by Gray and Wawer on pages 351–2.)
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.
Oxford University Press