Antibody response of HIV-infected patients to latent, cerebral and recently acquired toxoplasmosis

The aim of this longitudinal study with 626 HIV-infected patients was to evaluate the capability of serological tests in diagnosing the presence of Toxoplasma gondii infection in HIV-infected patients, as well as the potential impact of various treatment regimes on serological results. Low IgG antibody levels and stable or declining titres predominated. IgM positivity occurred in ten patients (one seroconversion, seven latent, two cerebral toxoplasmosis). Complement fixation test (CFT) titres ≥1:32 imply that the relative risk of cerebral toxoplasmosis is 6.84 (95% confidence interval [CI] 1.44–32.5) but with a predictive value of only 14.0% (95% CI 5.3–27.9). Values of specific antibodies are not biassed by antiretroviral treatment and/or prophylaxis for toxoplasmosis, and the detection of specific antibodies is very useful in the identification of T. gondii infection in the HIV-infected population, but the role of serology in predicting the clinical manifestation of T. gondii infection is limited.