Objective   To investigate the influence of clonorchis sinensis/clonorchiasis epidemic caused by ecological environment changes in Weishan lake area after the South-to-North water diversion project of China.

  Methods   Epidemiological survey was performed on the natural environment. (Changes of water area and the infection of clonorchis sinensis/clonorchiasis buski in aquatic in weishan country)heath situation of the residents were investigated and the fresh stools from residents of lake areas were examined by improved kato-kato methods.

  Results   The expansion of water area and control of water contamination after the South-to-North water diversion project were suitable for the propagation and spreading of the middle host of aquatic. The infective rate of Pseudorasbora parva infected by etacercarias of Clonor chis sinensis was 3.14%. The infective rate of the cats infected by adult of Clonorchis sinensis was 38.46%. But Clonorchis sinensis the sporocyst, redia and cercaria were not found in the freshwater Parafossarulus striatulus and Alocinma longicornis. Knowledge of Clonorchis sinensis/Clonorchiasis prevention and cure were short in the residents and the infection rate of fasciolopsis buski was 0.06%.

  Conclusion   Changes of the ecological environment in weishan lake area and the unhealthy life style of the presidents may lead to the epidernic and spreading of Clonorchis sinensis/Clonorchiasis, but widely propagation of Clonorchis sinensis/Clonorchiasis prevention and cure knowledge and some methods can prevent the epidemic of Clonorchis sinensis/Clonorchiasis in the lake area.