Abstract
Routine examination of 16 native-born Puerto Rican, asymptomatic prisoners in a large federal penitentiary, revealed the presence of Schistosoma mansoni infection in 2. Both by physical examination, and laboratory evidence, no liver or spleen involvement was found. The diagnoses were established both by rectal biopsy on sigmoidoscopy, and rectal aspiration of mucus. The patients were treated with intravenous antimony potassium tartrate, and tartar emetic. A marked eosinophilic response, with transient elevation of the BSP (bromsulfalein) test occurred. A plea is made for routine examination of all native-born Puerto Ricans in a nonendemic area for the parasite.