Chu K Y, Dawood I K
Bull World Health Organ. 1970;42(4):569-74.
The present paper deals with longitudinal and cross-sectional methods of counting cercariae shed from Biomphalaria alexandrina in Egypt, both experimentally and naturally infected with schistosomes. By the longitudinal method, the daily output of cercariae was counted from the first shedding from experimentally infected snails and from the day of collection from naturally infected ones. The results show that the size of the snails at the time of shedding exerts a very large effect on the output of cercariae and that the numbers obtained in the laboratory are not representative of cercarial output in the field. By the cross-sectional method, the cercarial output in the first 24 hours from infected snails collected in different months from the field was counted. The results show that output is size-specific. When the size-specific output is adjusted to the size-composition of infected snails taken from the field, it is estimated that the daily output from infected snails in the field may be 957.7 cercariae. However, this number may vary with the season.
本文探讨了对埃及感染血吸虫的亚历山大双脐螺排出尾蚴进行计数的纵向和横断面方法，这些螺既有实验感染的，也有自然感染的。通过纵向方法，从实验感染螺首次排出尾蚴起以及从自然感染螺采集之日起，对每日尾蚴排出量进行计数。结果表明，排出时螺的大小对尾蚴排出量有很大影响，而且实验室获得的数据不能代表野外的尾蚴排出量。通过横断面方法，对从野外不同月份采集的感染螺在最初24小时内的尾蚴排出量进行计数。结果表明，排出量具有大小特异性。当将大小特异性排出量调整为野外采集的感染螺的大小组成时，估计野外感染螺的每日排出量可能为957.7条尾蚴。然而，这个数字可能随季节而变化。
