Fish-borne zoonotic trematodes (FZTs) affect more than 40 million people worldwide (WHO, 2004). Liver flukes (Opisthorchiidae) are known best because of their clinical importance (WHO, 2011). Intestinal flukes (e.g. Heterophyidae) causes severe pathology in humans (Toledo et al., 2006), but impair food safety and quality, which has consequences for public health (Yu and Mott, 1994; Chai et al., 2005). The life-cycle of FZTs involves three types of hosts, primary intermediate snail host, secondary intermediate fish host, and final host like humans, pigs, cats or fish eating birds (Komiya, 1966; Sithithaworn et al., 2008). In this paper we focus on the role of snails. Asexual reproduction within the snail results in the release of cercariae over a period of months to years (Esch et al., 2002) and these cercariae might cause infection in fish which in turn are the reason for the food safety concern associated with FZTs.