Long-term impact of antiretroviral therapy (ART) on sexual HIV-transmission risk in Africa is unknown. We assessed sexual behavior changes and estimated HIV-transmission from HIV-infected adults on ART in Uganda.
Between 2003 and 2007, we enrolled and followed ART-naive HIV-infected adults in a Home-based AIDS program with annual counseling and testing for cohabitating partners, participant transmission risk-reduction plans, condom distribution and prevention support for cohabitating discordant-couples. We assessed participants' HIV plasma viral load and partner-specific sexual behaviors. We defined risky-sex as intercourse with inconsistent/no condom-use with HIV-negative or unknown sero-status partners in previous 3-months. We compared rates using Poisson regression models, estimated transmission risk using established viral load-specific transmission estimates, and documented sero-conversion rates among HIV-discordant couples.
Of 928 participants, 755(81%) had 36-months data: 94(10%) died and 79(9%) missing data. Sexual activity increased from 28% (baseline) to 41% (36-months (p < 0.001). Of sexually active participants, 22% reported risky-sex at baseline, 8% at 6-months (p < 0.001), and 14% at 36-months (p = 0.018). Median viral load among those reporting risky-sex was 122,500 (IQR: 45,100-353,000) copies/ml pre-ART at baseline and undetectable at follow-up. One sero-conversion occurred among 62 cohabitating sero-discordant partners (0.5 sero-conversions/100 person-years). At 36-months, consistent condom-use was 74% with discordant partners, 55% with unknown and 46% with concordant partners. Estimated HIV transmission risk reduced 91%, from 47.3 to 4.2/1000 person-years.
Despite increased sexual activity among HIV-infected Ugandans over three-years on ART, risky-sex and estimated risk of HIV-transmission remained lower than baseline levels. Integrated prevention programs could reduce HIV-transmission in Africa.