Toxoplasmosis is a ubiquitous infection, contracted by at least a third
of the population in most areas of the globe. Clinical disease arises
rarely, usually unexpectedly, but sometimes with disastrous effects on
the patient. Humans, pets, farm and zoo animals may contract
toxoplasmosis, possibly involving any clinical laboratory in its
diagnosis. Pathologists must ponder the clinical significance of a
hyperplastic l. ymph node, a cyst found at autopsy, or a serologic
titer. Serving as scientific physicians, pathologists are asked: How is
toxoplasmosis diagnosed? 'What is the treatment for ocular
toxoplasmosis, for congenital infection, or for toxoplasmosis in the
immunologically compromised host? vVhy does disease develop in as
diverse areas as the eye, lymph nodes and placenta? How is Toxoplasma
transmitted? This review proposes to survey recent advances, providing a
scientific background to diagnose and manage the clinical problems of
toxoplasmosis. Reviews are available which emphasize other aspects, such
as serologic pro- cedures, resistance and immunity (REMINGTON, 1970),
the clinical syndromes (DESMONTS, '1969; FELDMAN, 1968) and
comprehensive presentations (JACOBS, 1967; FRENI{EL, '1970).
Transmission and Prevalence The recent discovery of the coccidian stages
of Toxoplasma in the cat intestine and the Toxoplasma oocyst excreted in
cat feces, considerably broadens our understanding of Toxoplasma and its
transmission (FRENKEL, DUBEY and MILLER, 1970).