Toxoplasmosis and TB are more common in tropical areas where the prevalence of latent infections with Toxoplasma gondii and Mycobacterium tuberculosis in the general population is high. Headache, lethargy, confusion, seizures, and focal signs evolve over days to weeks. CT findings include ring-enhancing lesions with a predilection for basal ganglia. Serologic tests for IgG antitoxoplasmal antibodies reflecting previous infection are almost always positive but do not always provide conclusive proof that the lesion is caused by Toxoplasma organisms. The CSF shows a mild to moderate pleocytosis and elevated protein content.
Brain biopsy can be diagnostic.
Prognosis is at best guarded, since recurrence is possible and other complications of AIDS are likely. Progressive multifocal leukoencephalopathy and infections with Candida, Aspergillus, and gram-negative organisms occur less frequently. It may be clinically silent or may produce focal signs consistent with its anatomic location. Adequate primary prophylaxis for fungal, mycobacterial, and toxoplasmal infections is desirable but has not yet been developed. Secondary prophylaxis is indicated to prevent relapses of P. carinii pneumonia, cryptococcal infections, toxoplasmic encephalitis, herpes simplex, and thrush.