Analysis of Epidemic Factors of Clonorchis sinensis / Clonorchiasis in Shandong Province

It was found to have the prevalence of Clonorchis sinenesis (C.sinensis/Clonorchiasis) in Shandong in 1962. Out of 139 counties,107 were prevalent at different level throughout the province. From 1960～1970s, the average infection rate of human was 1.51%,the infection rate at village level of 1%～30%, and 85.7% of the infected population were children under 15 year. After integrate control for many years up to 1990s, the infection rate of humans C.sinensis decreased to 0.3%, 91.6% of villages infection rate was down to below 1%, and no cases were examined in 40% of the former endemic counties and 81% of the infected were above 21 year. After 1990s, owning to lating drought, 75% of ditches and pools were dried up and more than 90% of rivers were polluted. The living condition and the number of the intermediate host obviously reduced than before. Although the infection rate of fishes was about 50% lower than that of 1970's, the infection rate still remained about 30%. Because 97.9% of human changed the custom of living, without eating raw or poorly done style, the infected chance of human reduced. The results demonstrated that transmission condition for C.sinensis gradually reduced, and the endemic range obviously dwindled, and the infection rate of human decreased to 0.3% in Shandong. Therefore the transmission of C.sinensis is under control.