National strategy for serological diagnosis of HIV infection

The World Health Organization Global Program on AIDS recommends using one of three HIV testing strategies according to the objective of testing. Strategy 1 is to test all sera with one ELISA or rapid/simple assay with reactive sera considered to be HIV antibody-positive; nonreactive sera are considered HIV antibody-negative. Under strategy 2 all sera are tested first with one ELISA or rapid/simple assay with nonreactive sera considered HIV antibody-negative. Sera found to be reactive on the first assay however are retested with ELISA or rapid/simple assay based upon a different antigen preparation and/or different test principle. Sera which are reactive on both tests are then considered HIV antibody-positive. The procedure followed in strategy 2 is used in strategy 3 except that a third test is conducted upon a serum if it was reactive on the second assay. All three tests should be based upon different antigen preparations and/or test principles. Sera reactive on all three tests are then considered HIV antibody-positive. Serum which is reactive on the first and second tests but nonreactive on the third test is considered discrepant and should be referred to a reference laboratory. The AIDS Advisory Group of the Department of National Health and Population Development formed a subcommittee in February 1992 to recommend national strategies for the HIV testing of sera in South Africa. Strategy 1 should be followed when testing blood organs and tissues for donation. For surveillance strategy 2 is recommended in populations where the prevalence of HIV infection is equal to or less than 10% while strategy 1 is called for in populations of higher infection prevalence. Surveillance testing in South Africa should currently follow strategy 2. Strategy 2 is recommended for testing all patients with symptoms suggestive of HIV infection and all asymptomatic patients drawn from populations where seroprevalence is greater than 10%. Strategy 3 however is recommended for testing all asymptomatic patients drawn from populations where seroprevalence is 10% or less.