DISSEMINATED TOXOPLASMOSIS AND ACQUIRED-IMMUNODEFICIENCY-SYNDROME - DIAGNOSIS BY TRANSMISSION ELECTRON

A 43-year-old, bisexual, black man with acquired immunodeficiency synd rome (AIDS), detected by CD4 lymphocyte criteria alone, presented with low-grade fever, chills, malaise, and watery diarrhea of 2 days' dura tion. Over the next 5 days, he developed a fulminant septicemia-like i llness with progressive hypotension, disseminated intravascular coagul ation, and very high serum lactic acid dehydrogenase (2,150 U/L) and s erum creatine phosphokinase (5,395 U/L) levels, and died. The cause of this illness was not clinically apparent. A bone marrow biopsy perfor med on the day of his death revealed intracytoplasmic clusters of 3 mu m long, oval, basophilic organisms, the exact nature of which was not evident by light microscopy. The diagnosis of disseminated toxoplasmo sis (DT) was made only after electron microscopic study of the bone ma rrow revealed organisms with features typical of Toxoplasma gondii tac hyzoites. These features included a multilayered pellicle, a pointed a nterior end containing a conoid, up to nine rhoptries, sparse micronem es, and a posterior end containing a nucleus. Some of the organisms ha d divided by internal budding or endodyogeny. This case illustrates th e value of transmission electron microscopy in making the diagnosis of DT.