Acquired toxoplasmosis. A neglected cause of treatable nervous system disease.

The neurological manifestations of six cases of acquired central nervous system toxoplasmosis are compared with the 39 well-documented cases from the literature. Half of the patients had underlying systemic diseases (18 malignant neoplasms, two renal transplants, three collagen vascular diseases) treated with intensive immunosuppressive therapy. The remainder had primary toxoplasmosis. Three major neurological patterns were seen: (1) diffuse encephalopathy with or without seizures, (2) meningoencephalitis, and (3) singular or multiple progressive mass lesions. Routine neurological diagnostic studies were not helpful. The Sabin-Feldman dye test or IgM indirect fluorescent antibody test or both were effective in confirming the diagnosis. Twenty-seven patients died without a clinical diagnosis of toxoplasmosis. The diagnosis was made terminally in four additional patients. Thirteen of fourteen patients who received a full course of sulfadiazine or pyrimethamine or both did well. Toxoplasmosis should be considered in the immunosuppressed patient who appears with neurological involvement.