Morphology and diagnostics of human toxoplasmosis

Toxoplasmosis has regained clinical importance. In addition to intrauterine fetal infections, the acquired toxoplasmosis endangers an increasing number of immunocompromised adults. This disease affects not only oncologic patients, but also organ transplant recipients and, above all, AIDS patients. Toxoplasmosis has five clinical subtypes: lymphadenopathy, encephalitis, chorioretinitis, disseminated toxoplasmosis and congenital toxoplasmosis. In biopsies of different organs and autopsies of persons who died as a result of an infectious disease, the pathologist is involved in the diagnostic procedures. The findings of the parasites in tissue specimens still constitute the morphologic feature of toxoplasmosis. Differential diagnosis has been improved by immunohistologic methods for demonstrating toxoplasmas in tissue specimens and by the use of polymerase chain reaction for identification of toxoplasmatic antigens. This review describes the pathomorphology and possibility regarding the diagnosis of toxoplasmosis.