Abstract: Objective To explore the forming cause of the Oncomelania hupensis snail-existent non-endemic areas of schistosomiasis(SENEAS) in Bowang District, Ma'anshan City, and to provide the scientific evidence for schistosomiasis control measures in the area. Methods Field surveys were carried out in SENEAS in Bowang District for the infection rate of population and livestock, and the distribution of Oncomelaniasnails. In lab investigation, Oncomelania snails collected from SENEAS in Bowang District were randomly divided into two groups. They were exposed to Schistosoma japonicum miracidia and the ratio of snail to miracidia were 1 ∶ 20 and 1 ∶ 40, respectively. The same measures were used in Oncomelaniasnails from endemic areas in Huashan District as control groups. All snails were bred at room temperature for 90 days. Snail infection rate were observed and compared. Results In field research, we have investigated 568 people, 40 livestock , and 1 100 Oncomelaniasnails in SENEAS. The infection rate of population and livestock were both 0, and no positive snails were found. In lab investigation, the infection rate of snails in SENEAS were significantly lower than those in endemic areas in both 1 ∶ 20 group and 1 ∶ 40 group. Conclusion In SENEAS in Bowang District, Oncomeania snails can successfully infected by Schistosoma japonicummiracidia. We believed that the main reason of SENEAS is that there were no sufficient amount of infection source imported, and the low susceptibility to Schistosoma japonicum miracidia of local Oncomeaniasnails.

Key words: Oncomelania hupensis snail-existent non-endemic areas of schistosomiasis ( SENEAS ), Schistosoma
japonicum, Oncomelania hupensis, Susceptibility