parasitological study on lymnaea palustris and its ecological survey by gis in mazandaran province

objective: lymnaea palustris was previously found in mazandaran province but there was not any report about its parasitologic aspects. this study was conducted to finding ecological and parasitological aspects of snail in mazandaran province, north of iran. materials and methods: in this descriptive study, more than 181 locations, were checked, in 36 locations, colonies of the snail were found and 490 snails were collected. after diagnosis of snails as lymanea palustris, in laboratory, they were crushed and their probable cercaria was checked out by a dissecting microscope. data were analyzed and processed by arcgis 9.2 and microsoft office 2003 for descriptive analysis. results: from 490 snails, 6 cases (1.22%) were infected with trematode larval stage. these cercariae were classified as echinostomaercaria. optimum temperature for the snails was 15-19 degrees of celsius and optimum dissolved salt (tds) was 200-400 ppm. population of colonies were raised in autumn and winter but infected snails were seen in summer. conclusion: this study could show the ecological pattern, distribution, and population dynamic of the snail. also the existence of echinostomaercaria which is cercaria, generally belong to the echinostoma sp, indicates veterinary and parasitological importance of local snails. it is probable these parasite, infect man also. more studies on definitive host and exact species of parasite are proposed.