Failure to diagnose fatal disseminated toxoplasmosis in a bone marrow transplant recipient: the possible significance of declining antibody titres.

A 46-year-old patient with acute myelogenous leukaemia developed lethal disseminated toxoplasmosis 8 weeks after allogeneic bone marrow transplantation. Clinical features included pulmonary infiltrates, respiratory insufficiency and neurological signs. Post-transplantation toxoplasma serological tests were characterised by declining IgG titres and failure to detect IgM, whereas titres of IgG against the various herpes viruses remained constant and even increased over the same period. Circulating toxoplasma antigen could not be detected. Post mortem, specific immune complexes were identified in serum. Autopsy revealed widely disseminated toxoplasmosis with several foci in the brain, lungs and various other organs as well as concomitant infection with cytomegalovirus.