Cementing ditches of the habitat of oncomelania nosophora, the intermediate host of schistosoma japonicum, as a preventive measure of schistosomiasis - A review

Abstract

In Japan the main effort for the control of schistosomiasis has been directed to the control or eradication of Oncomelania nosophora, the vector snail of Schistosoma japonicum. And one of the chief measures for snail control is cementing of irrigation ditches for rice fields, the main habitat of vector snails. The effect of the cementing ditches for the control of the snail is considered as follows. 1. The majority of snails are buried in soil during the process of cementing and killed sooner or later. 2. The cemented ditches supply the snails no food and make it difficult for them to lay eggs. 3. In cemented ditches with inclination snails are removed more rapidly by the force of water faciliating the application of molluscicides. Up to the year of 1965, about 50 % of all ditches in endemic areas have been replaced by cemented ones. And as a result of the control of vector snails in endemic areas the population density of snails as well as the incidence of schistosoma infection decreased markedly in recent years. © 1965, National Institute of Infectious Diseases, Japanese Journal of Infectious Diseases Editorial Committee. All rights reserved.