OverviewToxoplasmosis is the leading cause of focal central nervous system (CNS) disease in AIDS. CNS toxoplasmosis in HIV-infected patients is usually a complication of the late phase of the disease.Typically, lesions are found in the brain and their effects dominate the clinical presentation. Rarely, intraspinal lesions need to be considered in the differential diagnosis of myelopathy.The decision to treat a patient for CNS toxoplasmosis is usually empiric. Primary therapy is followed by long-term suppressive therapy, which is continued until antiretroviral therapy can raise CD4+ counts above 200 cells/L.Prognosis is guarded. Patients may relapse because of noncompliance or increasing dose requirements.

PathophysiologyCNS toxoplasmosis results from infection by the intracellular parasite Toxoplasma gondii. It is almost always due to reactivation of old CNS lesions or to hematogenous spread of a previously acquired infection.[1] Occasionally, it results from primary infection.CNS disease occurs during advanced HIV infection when CD4+ counts are less than 200 cells/L. The greatest risk is in patients with CD4+ counts below 50 cells/L.[1]