A comparative study of the shedding of cercariae of Schistosoma haematobium in newborn Bulinus truncatus.

A comparative study of the shedding of cercariae of Schistosoma haematobium was performed in Bulinus truncatus and Planorbarius metidjensis individually exposed to 5 miracidia in their first 72 h of life. No significant difference was noted between the mean values of the two snail groups concerning the prepatent period duration (53-57 days at 24 degrees-26 degrees C), the patent period duration (41 days for B. truncatus, 70 days for P. metidjensis), or the total number of cercariae (1,499 per B. truncatus, 1,935 per P. metidjensis). Successive periods of heavy and low production were encountered in the shedding of cercariae; however, the periodicity was identical in the two snail species (25-27 days) and the emergence of cercariae peaked between 11 a.m. and 1 p.m.