Basic Biology and Tropistic Behavior of Schistosoma Mansoni Cercaria Relating to Cercaricidal Agents and Cercarial Repellents

摘要

The predatory activity of larvae of the Japanese firefly (Luciola cruciata) as well as the leech Helobdella triserialis and the operculate snail Ampullaria sp on newly hatched snails and egg masses of Biomphalaria glabrata was investigated. The results obtained with the intradermal test using as antigen a purified proteolytic fraction isolated from S. mansoni cercariae support the assumption of Lewert et al. that the cercarial enzyme inhibitor present in sera from schistosome patients probably represents a specific anitbody. A new chemoprophylactic agent (14, 15-epoxygeranylgeraniol) was isolated and chemically identified from the crude oil of Pterodon pubescens seeds. Farnesoic acid was shown to protect mice against infection by S. mansoni cercariae, in contrast to farnesol which was found inactive. The active constituents of Vetiver and Fennel oils in protecting mice against the infection by S. mansoni cercariae are being isolated and chemically identified. (Author)