Study On The Urban Schistosomiasis Control Projects

Objective:To evaluate the molluscicidal effect of the first phase of schistosomiasis comprehensive control preliminarily in Hankou Marshland,and providing a decision basis for further reducing the snail density and changing the breeding environment of snails.Methods:Put the first phase of schistosomiasis comprehensive control in Hankou Marshland as the research project,and use the method of combing mollusciciding and engineering modification for comprehensive schistosomiasis control such as taking measures of surface barrier removal,drug molluscicide,flatting surface,topsoil stripping,topsoil covering and ditch renovation to renovate.Monitoring the snail before the comprehensive implementation,during and after the regulation of the project by using the method of standardized,informative snail investigation,then understanding the change of monitoring indexes such as snail area,positive snail area,infection density of snail,active screw average density,snail infection rate before and after the comprehensive improvement of river beach regions,and evaluate the effect of comprehensive improvement of Hankou Marshland snail control afterwards.Results:In this comprehensive project,the total length and the remediation area were 2700km and 305500 square meters,respectively.Its mainly completed work of the project including 61100 cubic meters of topsoil landfill 305500 square meters of topsoil covering and 71800 cubic meters of excavation.Mollusciciding has been conducted for four times and the accumulative snail control area is 1224300 square meters.The whole comprehensive improvement of area has covered over 90%of Marshland area.Information-based screw survey has been conducted for 4 times and the total survey area is 122400 square meters.In the Information-based screw survey before the schistosomiasis control integrated treatment conducting,screw area is about 256900 square meters and there are 4498 box in the snail survey including 659 snail boxes,and the rate with snails isl4.65%.In the snail survey,there are 3346 snails obtained including 2751 live snails.The average density of snails is 0.44 snail per square meter,and the highest density of snails is 42.00 snail per square meter.In addition,no infected snail was found after the program conducted.The beach is flat after the renovation,the average length of the new groove,the groove top width,groove depth,height difference,the average value of slopes and ditch bottom slope have been increased.While the average value of the width and height of the ditch have been decreased.At the same time,Marshland beach surface has formed a new slope that the embankment is higher than the river.Conclusions:The snail breeding environment in Hankou Marshland has been effectively improved after the program conducted.The preliminary evaluation of the combination of mollusciciding and environmental modification has got a good result for snail controling.However,constant monitoring and comprehensive prevention are still demanded in snail polluted area to consolidate the snail control effect.