洲垸型渠道钉螺分布特点及形成易感地带因素研究

江陵县资市镇是洲垸型渠道地区的血吸虫病重流行区。1992年居民感染率为29.5％。耕牛血清学检查阳性率为66.7％。垸内渠道共有66条,面积30万m~2。其中有螺渠道占97.0％,有螺面积占99.3％;感染螺渠道占7.6％,面积占18.3％。主要分布在支、干渠内,分别占45.2％、39.8％。支、干渠是牲畜放牧,尤其是牛嬉水主要场地,经搜集野粪检查血吸虫卵和水体尾蚴分布调查结果表明,牛粪是污染水体感染钉螺的主要因素。支、干渠不仅感染螺平均密度及钉螺自然感染率高,而且有感染螺分布的面积大,是洲垸型渠道中的易感地带。

STUDIES ON CHARACTERISTICS OF SNAIL DISTRIBUTION IN CANAL AREA INSIDE EMBANKMENT AND FACTORS FORMING HIGH RISK AREA OF SCHISTOSOMIASIS

Zishi township of Jiangling city is located in the canal area inside embankment,a heavy endemic area of schistosomiasis japonica in Hubei province. The population and cattle preva-lence was 29.5% and 66.7% respectively in 1992. There are 66 canals and it covered a total area of 300000m2. 97.0% of the canals and 99.3% of the total area had snail inhabitants, and 7.6% of the snails distributed in canal was infected which covered 18.3% of the total area. The snails were mainly distributed in the main canal and their branches. The rate of snail distribution was 45.2% and 39.8% respectively. Cattle was pastured all year round in this area. Examination of scattered cattle feces and water revealed that the major factor of water contamination was scattered cattle feces. It explained why the infection rate of snail was high and the distribution of infected snail was extensive and how the major high rise area inside embankment was formed.