河道型钉螺孳生地环境特点及灭螺措施

目的 掌握河道型血吸虫病流行区钉螺孳生地的环境特点,提供最优的灭螺措施.方法 选择湘江河长沙段钉螺孳生地现场,进行钉螺分布、钉螺扩散、水文、泥沙和3种灭螺措施效果的观察.结果 湘江长沙段18块洲滩有钉螺分布,面积839 99 hm2.钉螺逆水向上游扩散,年平均可达17.5 km.洲滩的植被93%以上是莎草.湘江水体含沙量较大,汛期5-10月占全年输沙量的70%,因河道水流不畅,所以每年洲滩都有泥沙淤积,厚度一般为1.0 cm,部分低洼地带或水流缓冲处可达7.0 cm左右.湘江一般4月上旬开始涨水,最高洪水位多见于5-7月,最高洪峰持续时间较短,8月开始退水.3种灭螺措施效果比较,实施土埋和翻耕垦种灭螺措施的6块洲滩,灭螺效果好,其中3块效果考核没有发现钉螺,另3块活螺平均密度均减少了95%以上.每年坚持药物灭螺处理的7块洲滩,灭螺效果差,活螺密度没有变化,其中有3块洲滩发现了感染性钉螺.结论 钉螺向上游扩散同样具有较快的速度;洲滩植被以莎草为主;洲滩泥沙淤积主要是5-10月;湘江涨水和退水时间均较长江早;洲滩环境改造灭螺效果好,药物灭螺效果差.

Environmental Characteristics of River-beach Habitats and Snail Eradication Methods

Objective To investigate the environmental characteristics of habitats in river- beach type endemic areas, and explore the optimal measures for eradicating the intermediate host snails.Method The habitats areas in Changsha section of Xiangjiang River were chosen as the study pilots.The snail distribution,snail- spreading,hydrology and silt were investigated,and the effects of three snail eradication measures were observed.Results Snails were found in 18 grass - beaches,and the total snail - ridden area is about 839.99hm~2.The snails spread from the down - stream to the up - stream, and the annual average spreading speed was 17.5 km.More than 93% vegetation belongs to Crperus sp.Because of flood- ing,the annual average silt speed on the beaches was about 1.0 cm,and the highest reached 7.0 cm in some low areas. Compared to the other two methods,snail elimination by burying,reclamation and plantation had excellent effect.Among the 6 experimental beaches,no snail was found in the 3 beaches through snail eradication effect assessment,and the snail density was reduced more than 9.5 % in the other 3 beaches.Conclusion The snails could spread from the down - stream to the up - stream.Crperus sp is the dominant vegetation on river beaches.Snail eradication by environmental modification has good effects.