Analysis of re-emergence of Oncomelania snail in Sichuan Province from 2015 to 2019

ObjectiveTo analyze the risk of re-emergence of Oncomelania snail(O.snail) from 2015 to 2019, in order to improve the effectiveness of snail control.

MethodsCollection of report forms and schistosomiasis surveillance data was carried out from 2015 to 2019, and analyzed retrospectively.

ResultsThe area of snail-emergence was 6 241.98 hm² during 2015-2019, 44.29、4 610.18、813.92、446.09 and 327.50 hm² respectively, for each corresponding year.Among the re-emergence areas, flat-ground subtype was 1 185.49 hm²(18.99%), hilly subtype was 2 536.58 hm²(40.64%), and mountain subtype was 2 519.91 hm²(40.37%).The top 5 cities with O.snail re-emergence areas were Liangshanzhou(2016), Ya′an(2016), Deyang(2016), Meishan(2016), and Meishan(2017).The top 5 disticts with O.snail re-emergence areas were Renshou, Puge, Lushan, Tianquan and Dechang.

ConclusionThe re-emergence of O.snail attributes to several factors, such as low quality of annual snail survey, unitary method of elimination and complexity of snail habit environment.Surveillance and supervision on the sources of infection and snail spreading should continue with exploration of new method in eliminating snails especially in hilly regions.