Aspects of schistosomal endemicity in three Puerto Rican watersheds.

Abstract

SummaryA study of three Puerto Rican communities, each in a different watershed, was made with respect to group culture, distance from stream, waste disposal, contact with water, snail populations, snail infections, and the manner in which these factors influenced schistosomiasis endemicity. During the course of a 2-year period, 289 identified children of both sexes, ranging in age from 1 through 16 years, were surveyed quarterly for schistosomiasis, ascariasis, trichocephaliasis, and necatoriasis. The communities selected for study included a low class rural culture, a low class suburban culture, and a lower middle class suburban culture. Over-all schistosome infection rates of 69, 26, and 18%, respectively, were found in the three areas. Only 1% of 10,514 snails tested were positive. Factors associated with high schistosomiasis infection rates were poor means of waste disposal, frequent use of infested streams, and relatively large numbers of infected snails.