ABSTRACT
Objective To evaluate the fun ct ioning status and the effects of snail control in the different kinds of sluices in Dongting Lake regions. Methods Field invest igation was conducted for 85 modified sluices which aimed to preventing snails f rom spreading from 2000 to 2001 in Dongting Lake regions. The survey was used fo r the collection of data in terms of snails' situation in the irrigation canals and ditches inside the embankments where those modified sluices served as the in tervention of schistosomiasis control. The field trials of 85 sluices in 4 kinds (the abandoned, the equipped with lengtlened and lowered underwater pipes, the affiliated by snails retention tanks and the equipped with nets). were carried out to observe their effects of filtering snails, during which a g iven number of snails were cast in the front of the projects and recollected in the rear of the ones by means of the nets framed 40 holes per 25.4 mm.Results Eight sluices with the lengthened an d lowered underwater pipes were on trial for 22-28 hours and during which 2000 dyed snails was cast, yet no snails were detected in the rear. In 10 abandoned s luices, 9 were firmly sealed according to their design, and their functions of d rainage and irrigation inside embankment were replaced by other water conservanc y facilities. Up to 2003, 67 of 85 modified sluices have shown an effect on tra pping snails after 4-10 years of the running, and its effective rate arr ived at 78.8%. Conclusion Three kinds of sluices, i .e. the abandoned, the equipped with the lengthened and lowered underwater pipes , and the affiliated by snails retention tanks, show the capacity of trapping sn ail s, yet the one equipped with nets was unsuitable for application because of its difficulties in the long term maintenance. [