Résumé
Trematodes are a diverse group of endoparasites which require molluscan and vertebrate animals as intermediate and definitive hosts in their life cycle. The present study was carried out to determine the diversity and geographic distribution of infection with trematodes'cercariae in the snail Lymnaea gedrosiana from north-west Iran. A total number of 6759 Lymnaeidae snails were collected from 28 snail habitats; of these L. gedrosiana was the prevalent snail [74.37%] which examined for cercarial infection by shedding method. The overall infection rate was 8.03%. The most frequent trematodes cercariae in the snail were xiphidiocercariae [81.98%], furcocercariae [32.26%], echinostome cercariae [5.19%], and monostome cercariae [1.24%]. The highest infection rate in L. gedrosiana [100%] was with echinostome cercariae from Golestaneh in autumn. Due to the important role of pond snails in transmission of cercariae to fish as a source of zoonotic diseases, it is essential to estimate the distribution and abundance of the snails and the rate of their infection with different trema-todes' cercariae, and establish control programs in each region