Investigation on current distribution of Oncomelania snails in schistosomiasis-endemic areas of Sichuan Province / 中国血吸虫病防治杂志

ABSTRACT

Objective To understand the current distribution of Oncomelania snails in Sichuan Province, so as to provide scientific evidence for formulating the schistosomiasis elimination strategy and implementing the precision schistosomiasis control measures in the province. Methods According to the National Scheme on Oncomelania hupensis Snails in China and the Scheme on Oncomelania hupensis Snails in Sichuan Province, snail surveys were performed in current snail habitats, historical snail habitats and suspected snail habitats using systematic sampling in Sichuan Province from 2016 to 2017, and the survey results were analyzed. Results From 2016 to 2017, a total of 88 346 settings were surveyed in schistosomiasis-endemic areas of Sichuan Province, and 19 314 settings were detected with snails, covering an area of 4 829.25 hm2, with no Schistosoma japonicum infection identified in snails. A total of 3 017 915 frames were investigated in Sichuan Province, and 1 041 417 frames were found to have living snails, with totally 1 791 115 living snails captured. The mean density of living snails was 0.59 snails/0.1 m2, and the mean percentage of frames with living snails was 34.51% in Sichuan Province. The current snail habitats were mainly distributed in 1 704 villages, 377 townships, 54 counties (districts) of 9 cities (prefectures) across the schistosomiasis-endemic areas of Sichuan Province. Snail habitats were mainly found in ditches (70.22%), and weeds were the predominant vegetation in snail habitats (66.45%). Snails were firstly discovered in Sichuan Province in 1913, and S. japonicum-infected snails were firstly identified in 1956, with the latest identification of S. japonicum-infected snails in 2008. Conclusion There are many settings suitable for snail breeding in Sichuan Province, and snail monitoring and control should be intensified in the future.