The cercarial emergence rhythm of schistosoma mansoni in Ethiopia


Abstract: The cercarial emergence rhythm of Schistosoma mansoni from Biomphalaria pfeifferi of Ethiopia origin was studied in irrigation canals in Metehara Sugar Estate in December (1992), January and February (1993). Snails were allowed to shed cercariae individually in vials containing 2 ml of aged water and exposed to natural light between 800 hr and 1500 hr. In addition, batches of five swiss albino mice (Mus musculus) were exposed to canal water for an hour each between 800 hr and 1500 hr. The results indicate that peak cercarial emergence was between 900 hr and 1000 hr, while peak cercarial infectivity in mice was between and 1100 hr and 1200 hr. However, both cercarial emergence and infectivity in mice continued up to 1500 hr. These findings indicate that canal water can be used with less risk of schistosomiasis at least after 1500 hr, provided proper health education is given to the community.[Ethiop. J. Health Dev. 199-;0(0):0000]