[Analysis of Oncomelania hupensis status in schistosomiasis surveillance sites of Yunnan Province in 2015].

OBJECTIVE: To understand the Oncomelania hupensis distribution and infection status in the schistosomiasis surveillance sites of Yunnan Province, so as to provide the evidence for making the control and prevention measures. METHODS: Eighteen administrative villages were selected as the surveillance sites where the schistosomiasis endemic was serious in 18 epidemic counties, one village for one county. The snail status was investigated with the systematic sampling and environmental sampling methods, and the infection status of the snails was detected by a microscope and loop-mediated isothermal amplification (LAMP). The surveillance database was established and descriptively analyzed. RESULTS: In 2015, the total surveillance area was 1826.55 hm², and the area with snails was 55.03 hm², that was reduced by 57.70% as compared to that in 2013, and by 40.63% as compared to that in 2014. No new snail area was discovered, and also no schistosome infected snails were discovered. Totally 718,532 frames were surveyed, and the occurrence rate of frames with snails was 0.45% and the density of living snails was 0.013 9 snail/0.1 m². In the endemic controlled areas, the snail area and density of living snails were both the highest. The snails concentrated on the environments of paddy field, ditch, bottomland, small reservoir, and dry land, and the vegetations of rice, dry crop, weed and wood. The snail area, occurrence rate of frames with snails, total number of snails and number of living snails all showed a downward trend. No infected snails were found for three years. CONCLUSIONS: The Oncomelania hupensis snails have been effectively controlled in the national schistosomiasis surveillance sites of Yunnan Province. However, the comprehensive snail control measures still should be continually strengthened in order to consolidate the achivements.