Abstract:

Objective  To evaluate the effect of elimination of schistosomiasis infectivity in water
body by applying molluscicide on transmission marshland outside an embankment in Dongting Lake.
Methods  Two patches of transmission marshland with similar Oncomelania snails and infectious
snails density in the northern part of eastern Dongting Lake regions were selected as molluscicide
trail and control groups, respectively, and the snails and water body infectious indicators were in-
vestigated and compared between them. Results   Adjusted death rate of snails in the trail group 15
days after applying molluscicide was 94. 13% , without infected snails.  The infection rate of sentinel
mice in the trial group 50 days after applying molluscicide was 100. 00%, with average 56. 6 worms
per mice. The infection rate of sentinel mice in the control group without molluscicide was also
100. 00%, with average 147. 8 worms per mice.  Conclusions   In transmission marshland areas out-
side the embankment of rivers or lakes, it is impossible for focus mollusciciding to eliminate the in-
fectivity of schistosomiasis m water body, yet possible to reduce the degree of infectivity to a certain
extent.

Key words: Schistosoma japonicum, Transmission areas, Oncomelania snails, Molluscicide, Infectivity in water body

摘要：

目的评价药物灭螺消除湖区垸外易感地带水体血吸虫感染性效果。方法在东洞庭湖北岸选择钉螺和感染性钉螺密度大致相同的易感地带洲滩作为药物灭螺试验区和对照区，对比观察螺情和水体血吸虫感染性等疫情指标。结果试验区药物灭螺后15 d效果考核，钉螺校正死亡率为94.13%，未发现感染性钉螺；药物灭螺后50 d进行小白鼠感染性测定，感染率为100. 00%，平均虫荷56.6条／只；未灭螺的对照组小白鼠感染率亦为100.00%，平均虫荷147.8条／只。结论在面积较大的江湖洲滩，局部药物灭螺不能达到消除水体血吸虫感染性的目的，但起到了一定程度的降低水体血吸虫感染性的效果。

关键词: 日本血吸虫；易感地带；钉螺；药物灭螺；水体感染性