Ten years of laboratory diagnosis of HIV: how accurate is it now?

The high expectations of laboratory diagnosis of HIV have mostly been met, but some problems remain. Current tests for anti-HIV antibodies are sensitive enough for many purposes, but for earliest diagnosis direct tests for virus are necessary. False negative results may occur, for instance because infection with virus variants such as HIV 1 subtype O is not recognised, or because of laboratory or clerical error. The laboratory monitoring of mothers and babies who have been treated with zidovudine, to establish whether perinatal infection has taken place will be difficult, and more reliable quantitative assays of HIV are needed to measure the risk of transmission from mother to baby. Proposals to introduce home testing for HIV may improve ascertainment of infection, but there must first be adequate support in place for those individuals who find themselves HIV-positive. Quality assurance, especially through clinical and laboratory audit, may now add more to diagnostic accuracy than the development of even more sensitive assays. The outstanding challenge is to make universally available tests with the accuracy and consistency achieved when best laboratory practice is enforced.