Serological observations on toxoplasmosis in Zairian Aids patients

A retrospective serologic study was conducted to determine the incidence of toxoplasmosis in acquired immunodeficiency syndrome (AIDS) patients in Zaire. When AIDS infection is present the laboratory tests routinely used to detect toxoplasmosis (e.g. Sabin-Feldman dye test double-sandwich IgM-ELISA test and the indirect fluorescent antibody test) cannot be used reliably. Thus the investigators used 2 different serologic tests: 1) the indirect immunofluorescence test (IIFT) which uses the Remington test for IgM antibody and 2) the direct agglutination test (DAT) which treats sera with 2-mercaptoethanol to determine the role of the IgG in a positive reaction. 15 (13%) of the 108 AIDS patients studied had demonstrable IgM toxoplasma antibodies. The DAT detected 13 patients with IgM antibodies while the IIFT identified only 4. Toxoplasmosis was most frequently identified in AIDS patients with neurological signs (30%) and chronic diarrhea (15%). Residual antibodies to toxoplasma were identified in 32 (30%) of AIDS patients in this study when the IIFT was used and in 13 (12%) when the DAT was used. The authors have no hypothesis for the differences between the 2 tests used in this study. Reactivated latent toxoplasmosis has emerged as the most commonly recognized central nervous system infection in AIDS patients in Zaire. Thus all AIDS patients but particularly those with neurological signs and chronic diarrhea should be tested for possible toxoplasma infection.