Oncomelania hupensis status in national schistosomiasis surveillance sites of Yunnan Province from 2015 to 2017

Abstract

To master the Oncomelania hupensis distribution and infection status in the national schistosomiasis surveillance sites of Yunnan Province, so as to provide the evidence for making the control and prevention measures. The data of O. hupensis surveillance in the 18 national surveillance sites of Yunnan Province from 2015 to 2017 were collected and analyzed with the descriptive analysis method according to the national schistosomiasis surveillance programme. The total surveillance area was 5 710.94 hm2, the area with O. hupensis snails was 205.69 hm2. The number of surveillance frames was 2 094 553, the occurrence rate of frames with snails was 0.62%, and the density of living snails was 0.025 4 snails/0.1 m2. In the schistosomiasis epidemic controlled areas, the area with snails, the occurrence rate of frames with snails and the density of living snails were all the highest. The snail concentrated distribution areas were the small reservoir, bottomland, paddy field, ditch, and dry land, and the snails mainly distributed in the rice, dry crop, weed and wood vegetation. The number of frames with snails, occurrence rate of frames with snails, total number of snails, number of living snails, and repetition areas with snails presented increasing trends, and however, no schistosome-infected snails were found during the three years. The O. hupensis snail status is obviously serious in the national schistosomiasis surveillance sites of Yunnan Province. The comprehensive snail control measures should continue to be strengthened, so as to effectively control the spread of the snails and reduce the risk of schistosomiasis outbreaks.