Screening for 'window-period' acute HIV infection among pregnant women in rural South Africa.

OBJECTIVES: The aim of this study was to evaluate the HIV-1 RNA pooled nucleic acid amplification testing (NAAT) strategy to screen pregnant women in the 'window period' of acute HIV infection (AHI) in rural South Africa. METHODS: In 2007 and 2008, 750 consecutive pregnant women on their first antenatal care visit to a primary health care clinic were tested anonymously for HIV infection. HIV-1 RNA pooled NAAT was performed on HIV antibody-negative samples. All positive pools were tested individually and positive samples were classified as incident cases to calculate HIV incidence. RESULTS: The overall HIV prevalence was 37.3% [95% confidence interval (CI) 34.3­41.3]. Of the 467 HIV antibody-negative samples, four (0.9%) were HIV-1 RNA-positive. The mean viral load in the four samples was 386 260 HIV-1 RNA copies/mL (range 64 200­1 228130). The HIV incidence was 11.2%per year (95% CI 0.3­22.1) and all women with AHI were 21 years of age. CONCLUSIONS: Identifying AHI in pregnancy is important for health interventions to reduce perinatal and heterosexual transmission of HIV, and to estimate HIV incidence for epidemiological surveillance.