The life cycle of digenetic trematodes is
complicated[1]. To most species, snails act as
intermediate host, in which several developing larval
stages such as sporocysts, rediae and cercariae are
set up[2]. Moreover, freshwater snails can have an
important effect on trematodes. As they are extensively
widespread in freshwater streams, the trematodes are
able to produce high number of cercariae for their
transmissions. The outbreaks of parasitic infection have
been continually reported in Thailand, especially in
Chiang Mai province, Thailand. This area is covered by
diverse ecosystems of farm forestry, along with plenty
of water resources, producing a high biodiversity to