[Causes of re-emergence of Oncomelania snails in hardened ditches].

Objective: To understand the impact factors of the re-emergence of Oncomelania snails in hardened ditches so as to find out the measures to improve the effect of snail eradication.

Methods: Thirteen infected townships from Jingmen City were randomly selected and investigated with the retrospective method and the field survey. All the data were analyzed for evaluating the effect of the hardened ditches on snail eradication and finding out the causes of the re-emergence of snails in hardened ditches

Results: After on-site investigation of 151 hardened ditches, the eradication rate of snail areas was 78.