钉螺血吸虫感染率与粪便虫卵负荷、钉螺密度相关性的现场实验研究

目的研究自然条件下钉螺血吸虫感染率与粪便虫卵负荷、钉螺密度间的相关关系,探讨血吸虫病流行区达传播阻断所需的血吸虫负荷和/或钉螺密度阈值。方法采用两因素三水平的正交设计L9(34):虫卵负荷设为1 000、5 000和10 000个/m2,钉螺密度设50、100和200只/m2,共设置9个实验组。于秋季10月份用含血吸虫虫卵粪便现场感染阴性钉螺,次年春季4月份回收钉螺并压碎镜检钉螺感染情况。结果 9个实验组钉螺感染率在1.09%~25.53%之间;同等粪便虫卵负荷下,钉螺感染率随钉螺密度的降低而增高,1 000只虫卵组有统计学意义(P<0.01);经多因素方差分析,钉螺感染率与粪便虫卵负荷、钉螺密度无显著相关性且后二者无交互作用(F=3.930,P>0.05)。结论当钉螺密度≥5只/0.1 m2,秋季1 000个及以上血吸虫虫卵可致1 m2范围内的钉螺感染血吸虫。在钉螺感染环节中粪便虫卵负荷的作用似大于钉螺密度。

Field study on the correlation between the snail infection rate and the fecal egg load and snail density

Objective To ascertain the correlation between the snail infection rate and the fecal egg load and snail density under natural conditions and explore the thresholds for interruption of Schistosomiasis japonica transmission.Methods Nine experimental groups were established using an orthogonal design(L9(34)) with two factors(fecal egg load & snail density) and three levels.The levels of fecal egg load were 1 000,5 000,and 10 000 eggs/m2,and the levels of snail density were 50,100,and 200 snails/m2.Snails were...