Helisoma duryi一直被认为是血吸虫中间宿主的一种生物防制物。本研究的目的是了解有H.duryi孳生的水对亚历山大双脐螺逸出尾蚴量的影响。H.duryi采自美国佛罗里达州,亚历山大双脐螺采自埃及盖勒尤卜。曼氏血吸虫为埃及开罗株。分二个实验组。一组是测定水中化学成分的干扰作用。方法是用网筛把水族箱隔成二格,其中一格内放入20只H.duryi或阴 Helisoma duryi has long been considered as a biological control of the schistosome intermediate host. The purpose of this study was to understand the effect of H.duryi-infested water on the amount of escaped cercariae from Alexandrium. H.duryi was collected from Florida, USA, and Alexandria double snail was taken from Galleubur, Egypt. Schistosoma mansoni Cairo, Egypt strain. Divided into two experimental groups. One group is the determination of the chemical composition of water interference. The method is to use a mesh sieve into two aquariums, one of the grid into 20 H.duryi or Yin