Screening for 'Window-period' Acute HIV Infection among Pregnant Women in Rural South Africa

ABM Kharsany; N Hancock; JA Frohlich; HR Humphries; SS Abdool Karim; Q Abdool Karim


HIV Medicine. 2010;11(10):661-665. 

In This Article

Abstract and Introduction


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 386 260 HIV-1 RNA copies/mL (range 64 200–1 228 130). 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.


Epidemiological screening for HIV infection using standard antibody tests is crucial to understand and monitor the spread of HIV and to provide care and treatment for those who are infected.[1] In countries with generalized epidemics where heterosexual transmission is dominant, HIV seroprevalence surveys among pregnant women are frequently used. These surveys identify individuals with latent or advanced HIV disease and miss individuals with 'window-period' acute HIV infection (AHI), who are more likely to transmit HIV due to high viral concentrations in the blood and genital tract.[2,3] Sensitive, validated and well-calibrated assays for HIV-1 RNA and p24 antigen, and the fourth-generation assays for the simultaneous detection of HIV antibodies and p24 antigen, have been used with increasing frequency to diagnose AHI.[4–8] These tests have been used in cross-sectional studies to estimate HIV incidence[5,6] and are useful to understand HIV transmission dynamics and assess the impact of public health interventions.[9] The objective of this study was to evaluate the HIV-1 RNA pooled nucleic acid amplification testing (NAAT) strategy to screen pregnant women for 'window-period' AHI and estimate HIV incidence.


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