【摘要】 以1、5、10、20和40只5组不同数量的血吸虫毛蚴分别感染单只阴性钉螺后,对钉螺感染率、感染螺的逸蚴率,逸蚴量及存活时间等进行观察,结果进一步证实了钉螺感染率的高低与毛蚴数量的多少呈相一致的趋势。感染螺的尾蚴逸出率具有明显的季节性变化。观察的250只感染螺在4,064次逸蚴中,共逸出尾蚴287,213条,平均每螺每次逸蚴70.67条。每只感染螺在本次观察的整个生存期间中逸蚴数平均为1148.85±96.29条,最多为8.079条。5组感染螺平均逸蚴数之间无显著差别。感染螺的存活时间从毛蚴入侵螺体时计算,平均为214.25±9.89d,最长为936d(相当2年零7个月);从初次逸蚴时计算,平均为118.28±9.94d,最长为839d。各组感染螺的平均存活时间亦无显著差别。94.8％的感染螺均在开始逸蚴后1年内死亡。更多还原

【Abstract】 The infection rate of Oncomelania snails, emergence rate of Schistosoma japa-nicum cercariae, number of emerged cercariae and survival time of infected snails were observed experimentally by exposing single snails to different number of miracidia (i.e. 1, 5, 10, 20 and 40 respectively). The infection rate of snails was shown to be increased with the increasing number of miracidia. The frequency of cercaria emergence of infected snails varied significantly in different seasons and the highest was in spring and summer. No cercaria emergence was observed in winter. The average number of cercariae emerged from a single infected snail in each observation was 70.67, and through the whole lifetime in this experiment, 1,148.85±96.29. There was no significant difference in average number of emerged cercariae among the 5 groups of infected snails. The maximum number of cercariae emerged from one infected snail was 8,079. Calculated from the begining of cercaria emergence, the survival time of infected snails was in average 118.28±9.94 days, and the longest being 839 days. There was no significant difference in survival time among the 5 groups, and 94.8% infected snails died within one year.更多还原