The Molluscan Intermediate Host and Schistosomiasis Japonica

Introduction. The program of the Commission on Schistosomiasis included an attempt to determine the most successful method of maintaining colonies of the snail Oncomelania quadrasi (= Schistosomophora quadrasi) experimentally infected with Schistosoma japonicum. It was planned to expose uninfected, laboratory reared snails to determine the number of miracidia that would produce the highest infection and survival rates in the snails. Information was desired on the interval of time necessary for the production of cercariae after miracidia had penetrated the snail and also as to whether or not reproduction occurred among the snails kept under artificial conditions.Materials and Methods. After preliminary observations it became apparent that it was impossible to raise O. quadrasi in sufficient numbers or rapidly enough for use in the laboratory. Consequently, it was decided to select adult snails from areas in which infections with S. japonicum were absent or rare.