Meningoencephalitis caused by Toxoplasma gondii diagnosed by isolation from cerebrospinal fluid in an HIV-positive patient.

Toxoplasmosis of the central nervous system is a frequent opportunistic infection in AIDS patients, usually presenting as a mass brain lesion detected by computerized axial tomography scanning or magnetic resonance imaging. A case of diffuse meningoencephalitis with no radiological evidence of brain lesions is described. Diagnosis was made by culturing cerebrospinal fluid (CSF) on THP1 cells where tachyzoites of Toxoplasma gondii were demonstrated after 8 days of incubation by both direct observation and immunofluorescence. CSF examination with culture should be considered in AIDS patients with neurological signs and symptoms but without radiological evidence of cerebral lesions.