Human Sparganosis

A woman 66 years of age noted 2 subcutaneous nodules, 1 of which migrated from the right to the left side of the midline of her back. The pathologist's examination identified these and other lesions as tracts containing motile larvae of sparganum, the adult form of which is a tapeworm of a species ofDiphyllobothrium. Infestation with this parasite can probably be prevented by avoiding drinking water from natural sources, especially in areas where water snakes and other wild life are known to harbor the organism.