HIV incidence and prevalence among cohorts of women with higher risk behaviour in Bloemfontein and Rustenburg, South Africa: a prospective study

Objectives: The primary objective was to measure HIV incidence in two prospective cohorts of HIV-negative women. Secondary objectives included measuring pregnancy rates and participant retention rates. Design: Cross-sectional HIV screening of women selected for higher risk behaviours, with a subsequent prospective study of uninfected women, followed monthly for up to 6 months. Setting: Clinics established for research purposes in Bloemfontein and Rustenburg, South Africa. Participants: The authors enrolled women 18-35 years old and presumed at higher risk of sexual acquisition of HIV as indicated by self-reported sexual behaviour or recent sexually transmitted infection symptoms. In Bloemfontein, 1364 women were screened, 1154 were eligible for HIV testing and 1145 agreed to be tested. The prospective study enrolled 401 HIV-negative women. In Rustenburg, 946 women were screened, 540 were eligible and underwent HIV testing and 223 HIV-negative women entered the prospective study. Primary and secondary outcomes: Baseline prevalences of HIV infection and HIV incidence rates in the prospective cohorts, according to a double rapid test algorithm with a third rapid test for discrepant or indeterminate results. Pregnancy prevalences and pregnancy incidence rate in Bloemfontein. Participant retention rates in the prospective cohort until the study end. Results: In Bloemfontein, 1145 women were tested, 391 entered follow-up and 92.3% of participants completed six study visits. In Rustenburg, 540 women were tested, 194 entered follow-up and retention up to the point of early study termination was 88.6%. Overall HIV prevalence was 21.2% (95% CI 18.9% to 23.6%) in Bloemfontein and 23.5% (95% CI 19.9% to 27.1%) in Rustenburg. Overall HIV incidence was 5.5/100 person-years (95% CI 2.5 to 10.4) in Bloemfontein and 3.0/100 person-years (95% CI 0.4 to 10.8) in Rustenburg. Cross-sectional pregnancy prevalences were 6.5% in Bloemfontein and 8.6% in Rustenburg. Conclusions: The authors observed substantial HIV incidence rates in both cohorts. Vigorous prevention efforts are needed in these smaller cities.