关键词: 有螺无病区；血吸虫病；毛蚴；钉螺

Abstract: Objective To understand the forming cause of the Oncomelania hupensis snail?existent non?endemic areas of schistosomiasis （SENEAS）， and to verify the conclusion of previous studies， so as to provide the evidence for schistosomiasis monitoring in such areas in Nantong City， Jiangsu Province. Methods The controlled field tests were carried out to observe the O. hupensis snails artificially infected by schistosome miracidia in SENEAS. The influence of the soil from SENEAS and the endemic areas on O. hupensis snails artificially infected by miracidia were observed. Results All the experimental snails could be infected by schistosome miracidia except the smooth?shell snails from Tangyuan Village in the controlled field test environment of SENEAS or the endemic areas. The infection rates of the smooth?shell snails were lower than those of the ribbed?shell snails， but there were no statistically significant differences. The mortality rates of the smooth?shell snails were higher than those of the ribbed?shell snails， which were statistically significant （[χ2Xindian] = 135.118， [χ2Shuangdian] = 122.836， [χ2Baipu] =154.436，[χ2Dingyan] = 138.288， [χ2Control] = 151.923， all P < 0.01）. There were no significant differences in the infection rates of snails between each test group of the soil from SENEAS and the endemic areas （[χ2Rugao] = 0.071， [χ2Rudong] = 0.216， both P > 0.05）. Also there was no significant difference between each test group and the control group without soil （[χ2] = 7.148， P > 0.05）. Conclusion It is likely to form the spread of schistosomiasis in SENEAS in Nantong City with sufficient amount of infection source of schistosomiasis imported. It is still necessary to implement the surveillance of schistosomiasis and O. hupensis snails in Nantong City.

Key words: Snail?existent non?endemic area of schistosomiasis （SENEAS）； Schistosomiasis； Miracidium； Oncomelania hupensis