The landmark HIV Prevention Trials Network (HPTN) 052 trial in HIV-discordant couples demonstrated unequivocally that treatment with antiretroviral therapy (ART) substantially lowers the probability of HIV transmission to the HIV-uninfected partner. However, it has been vigorously debated whether substantial population-level reductions in the rate of new HIV infections could be achieved in “real-world” sub-Saharan African settings where stable, cohabiting couples are often not the norm and where considerable operational challenges exist to the successful and sustainable delivery of treatment and care to large numbers of patients. We used data from one of Africa’s largest population-based prospective cohort studies (in rural KwaZulu-Natal, South Africa) to follow up a total of 16,667 individuals who were HIV-uninfected at baseline, observing individual HIV seroconversions over the period 2004 to 2011. Holding other key HIV risk factors constant, individual HIV acquisition risk declined significantly with increasing ART coverage in the surrounding local community. For example, an HIV-uninfected individual living in a community with high ART coverage (30 to 40% of all HIV-infected individuals on ART) was 38% less likely to acquire HIV than someone living in a community where ART coverage was low (<10% of all HIV-infected individuals on ART).

Objectives To investigate HIV prevalence trends in a rural South African community after the scale-up of antiretroviral treatment (ART) in 2004. Methods We estimated adult HIV prevalence (ages 15–49 years) using data from a large, longitudinal, population-based HIV surveillance in rural KwaZulu-Natal, South Africa, over the period from 2004 (the year when the public-sector ART scale-up started) through 2011. We control for selection effects due to surveillance non-participation using multiple imputation. We further linked the surveillance data to patient records from the local HIV treatment programme to estimate ART coverage. Results ART coverage of all HIV-infected people in this community increased from 0% in 2004 to 31% in 2011. Over the same observation period adult HIV prevalence increased steadily from 21% to 29%. The overall increase in HIV prevalence was largely driven by the prevalence trends in women and men older than 24 years of age, i.e., the age group in which the largest proportions of HIV-infected people received ART. Conclusions The observed dramatic rise in adult HIV prevalence can be largely explained by increased survival of HIV-infected people due to ART. This interpretation is supported by the fact that the overall HIV prevalence trend is mostly due to increases in prevalence in older adults, i.e., in the age groups that currently benefit most from the local ART scale-up. Future studies should decompose HIV prevalence trends into HIV incidence and HIV-specific mortality changes to further improve the causal attribution of prevalence increases to treatment success rather than prevention failure.