Serologic validation of HIV infection in a tropical area

We have defined human immunodeficiency virus type 1 (HIV-1) serologic reactivity in Brazilians living in an area endemic for tropical diseases. Enzyme-linked immunosorbent assay (ELISA) and Western blot (WB) analyses were performed on 342 patients with diseases including Chagas' disease, schistosomiasis, typhoid fever, helminthiasis, and cutaneous and visceral leishmaniasis. Nine percent of the visceral leishmaniasis patients' sera reacted in the HIV-1 ELISA but all were WB negative. All other sera from these patients were HIV negative. A total of 224 HIV-1 ELISA repeatedly positive sera also were HIV-1 WB tested. They were drawn from a total population of 19,230 individuals, including AIDS patients, blood donors, homosexual men, intravenous drug users, pregnant women, individuals with hemophiliac, and tuberculosis and sexually transmitted disease patients. The WB results were analyzed using five different interpretive criteria for WB positivity. The Centers for Disease Control (CDC) and the World Health Organization (WHO) criteria were the most sensitive and specific for identifying HIV-1-infected individuals. The WB pattern was similar to that seen in the United States. Envelope (ENV) protein antibodies were highly predictive of HIV-1 infection; none of the AIDS patients lacked ENV protein reactivity. We conclude that among the tropical diseases studied, only visceral leishmaniasis is associated with false-positive HIV-1 ELISA tests. Current CDC and WHO criteria for interpretation of HIV-1 WB tests are appropriate for Brazil.