Experimental Toxoplasmosis

THE PROTOZOON toxoplasma has long been known to be pathogenic to a large variety of mammals and birds,1but interest in the organism was aroused only when Wolf, Cowen, and Paige2firmly established that the parasite causes a disease in human infants. Pinkerton and Weinman3subsequently showed that not only infants but also adults can have toxoplasmosis, a disease marked by variable clinical and subclinical manifestations. In very young children and babies, hydrocephalus, microcephaly, chorioretinitis, cerebral calcifications and psychomotor disturbances are observed most commonly,4while in older children acute, nonsuppurative encephalitis is also seen.5Relatively few cases of the disease in adults have been reported. A spotted-fever-like syndrome associated with atypical pneumonia appears to be the cardinal sign of the acute disease,6while chorioretinitis is probably a manifestation of a more chronic course.7There is now a considerable body of evidence to indicate