Toxoplasmosis of the central nervous system.

Toxoplasmosis is usually an asymptomatic infection, but symptomatic cases are becoming more common with the rise in AIDS cases and the increased number of patients receiving immunosuppressive therapy. Toxoplasmosis of the central nervous system occurs most often in immunocompromised hosts. Brain biopsy may be necessary for diagnosis. Pyrimethamine and sulfadiazine are active against T. gondii, but they do not affect the encysted organisms.