Schistosomiasis on Bohol Island, Philippines, with special emphasis on the successful discovery of new habitats of the vector snail, Oncomelania quadrasi, and area-wide mollusciciding.

Abstract

In the endemic area of schistosomiasis on Bohol Island, we succeeded in locating seven new colonies of the vector snail, Oncomelania quadrasi, four in Trinidad and three in Talibon, in addition to six locations from which the snails were previously recorded. We were led by the proximity of the snail habitat to the residence of the infected individuals. In northern Bohol the continuous wet season would appear to make the major differences between the places that do and those that do not support O. quadrasi. Twice-yearly weed clearance and applying chemical molluscicides (niclosamide and phebrol) for the control of O. quadrasi have been extensively in effect over the snail colonies, since July 1986. Although it has not yet yielded satisfactory results in certain colonies, snails have been eliminated from six habitats in a period of two and a half years.