Human immunodeficiency virus (HIV) antigen testing to detect HIV infection in female sex workers in Singapore.

Since the HIV p24 antigen appears a few weeks before the HIV antibody researchers conducted a study to determine whether the HIV antigen test Abbott HIV AG-1 would identify recently HIV-infected female sex workers in Singapore whose infection might be missed if only HIV antibody tests were used. During April 1993-April 1994 blood samples were taken from 1000 female sex workers newly enrolled in the Department of STD (sexually transmitted disease) Control of Singapore General Hospital to test for the HIV p24 antigen. Results of the Abbott HIV AG-1 test were compared with 3 HIV antibody tests (Abbott recombinant HIV-1/HIV-2 3rd generation enzyme immunoassay [EIA] test the Fujirebio Serodia-HIV particle agglutination [PA] test and the Diagnostic Biotechnology HIV Blot 2.2 Western blot [WB] test). All 3 HIV antibody tests found 25 female prostitutes to be HIV positive. The EIA and WB tests found 26 women to be HIV positive for a prevalence rate of 2.6%. Only 1 specimen tested positive for HIV antigen. This specimen also tested positive for HIV antibodies. There was no HIV antigen positive specimen that was HIV antibody negative or indeterminate. These findings show that the HIV antigen test did not improve the detection rate of HIV infection in these female sex workers since there were no HIV antigen specimens that were HIV antibody negative or indeterminate.