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

Abstract

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) 34.3–41.3]. Of the 467 HIV antibody-negative samples, four (0.9%) were HIV-1 RNA-positive. The mean viral load in the four samples was 386260 HIV-1 RNA copies/ml (range 64 200–1228130). The HIV incidence was 11.2% per year (95% CI 0.3–22.1) 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.