Disseminated toxoplasmosis in the acquired immunodeficiency syndrome.

Fourteen cases of toxoplasmosis in subjects at autopsy with acquired immunodeficiency syndrome are reviewed. Death was related to toxoplasmosis in four cases: in three from central nervous system complications and in one case from myocarditis. In six cases the infection was identified outside of the central nervous system and in only two cases was infection disseminated to multiple extracerebral organs. Review of clinical history and laboratory data revealed no specific risk factors or laboratory indicators associated with toxoplasmosis in acquired immunodeficiency syndrome. Though inflammatory cell infiltrates often accompanied disseminated infections, diagnosis could be made with certainty only by finding characteristic Toxoplasma organisms, either as free tachyzoites, pseudocysts, or as true parasitic cysts. We found immunohistochemical staining to have limited usefulness for diagnosis in extracerebral sites. Characteristic Toxoplasma organisms were most readily identified in central nervous system tissues in our acquired immunodeficiency syndrome population, making this the most useful site for diagnosis.