HIV testing and monitoring

Approximately one-third of HIV-infected persons in Europe and North America are unaware of their infection. There has been a call for doctors to improve the uptake of HIV testing, and for testing to be ‘normalized’ and incorporated into routine practice. Current screening tests allow the combined detection of HIV antibodies and p24 antigen, and can detect the infection within 6–8 weeks. Simple and rapid point-of-care tests are also available. Due to the presence of maternal antibodies, HIV diagnosis in children is based on the detection of viral nucleic acid in blood. Measuring the viral RNA in plasma (‘viral load’) plays a pivotal role in HIV management, and can be useful in diagnosing acute infection prior to the appearance of antibody and p24 antigen. Among untreated patients, the viral load predicts the rate of disease progression. In treated patients, it measures the success of antiretroviral therapy as a surrogate marker for immunological and clinical success. Drug resistance testing is also a key management tool, both in diagnosing transmitted drug resistance and in patients who experience treatment failure to guide drug selection.