Survival of beta and gamma races of Neotricula aperta snail intermediate hosts of Schistosoma mekongi in raw waters.

Beta and gamma races of Neotricula aperta were exposed to naturally raw waters of the Sirindhorn reservoir, Mun River and Mekong River in laboratory conditions and non supplement on food. Snails of two races could withstand well in variable qualities of water within 48 hours. The survival rates of N. aperta in three sources of raw water were 100% for the beta race and 97 to 100% for the gamma race.