Immunohistochemical demonstration of Toxoplasma gondii

A peroxidase-antiperoxidase method that demonstrates both free and encysted toxoplasmata in routinely prepared histologic sections is described. This technic and ultrastructural study were employed to confirm the presence of Toxoplasma gondii in the infected tissues of an immunosuppressed patient who had postmortem examination. An immunohistochemical method may be an aid in the diagnosis of toxoplasmosis.