Serological study of the prevalence of toxoplasmosis in asymptomatic patients infected with human immunodeficiency virus.

Asymptomatic individuals seropositive for antibody to human immunodeficiency virus (HIV) were investigated for the presence of toxoplasma specific antibody. Serological examination was performed using multiple assays. Of 500 patients studied 133 had serological evidence of previous exposure to Toxoplasma gondii. Specific IgM was detected in 7 patients using ISAGA and 2 patients by DS-ELISA. The immunoglobulin-G annual seroconversion rate was calculated to be 0.75%. The results of this study indicate 27% of HIV positive patients in the UK are at risk of developing life-threatening secondary reactivation of cerebral toxoplasmosis in association with AIDS. A further 0.5-1% per year may suffer primary toxoplasmosis.