Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 18 2 2023 06 26 182 192 Mojgan Aryaiepour 1. Student of Research Committee, Mazandaran University of Medical Sciences, Sari, Iran 2. Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Ramin Mazaheri Nezhad Fard Department of Medical Pathobiology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mohammad Bagher Molai Rad Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Majid Pirestani Parasitology and Entomology Department, Medical Sciences Faculty, Tarbiat Modares University, Tehran, Iran Soheila Rouhani Department of Medical Parasitology and Mycology, Shahid Beheshti University of Medical Sciences, Tehran, Iran Ahmad Daryani Toxoplasmosis Research Center, Communicable Disease Institute, Mazandaran University of Medical Sciences, Sari, Iran Tina Asadi Comparative Zoology, Institute for Biology, Humboldt University of Berlin, Berlin, Germany Shahabeddin Sarvi Toxoplasmosis Research Center, Communicable Disease Institute, Mazandaran University of Medical Sciences, Sari, Iran Mohammad Bagher Rokni Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran 2022 07 17 2023 04 10 Background: Identification of the larval stages of Echinostoma spp. in freshwater snails is an essential guide to continue monitoring the possibility of their transmission and the potential of echinostomiasis in areas where trematodes are the primary agent of parasitic diseases. The aim of this study was investigate Echinostoma using morphological and molecular techniques. Methods: The study was conducted in Gilan and Mazandaran Provinces, northern Iran, from April 2019 to October 2021. Overall, 5300 freshwater snails were randomly collected and were identified using external shell morphology. Meanwhile, snails infected with trematodes were studied via shedding and dissecting methods. Larvae stages of Echinostoma were identified and the genomic DNA of the samples was extracted. The PCR amplification of the ITSI gene was carried out for 17 isolates and products were sequenced. Seven sequences were deposited in GenBank. Results: Totally, 3.5% of snails containing three species (Stagnicola sp., Radix sp. and Planorbis sp.) were infected with two types of cercaria, E. revolutum with 37 and Echinostoma sp. with 45 spines in the collar. Moreover, 35% of the snails were infected with Echinostoma spp. metacercaria. Phylogenetic analysis illustrated that isolates were included in two ITSI haplogroups. Conclusion: Results showed the potential hazard of a zoonotic parasite as Echinostoma in northern Iran. The potential of disease environmental relationship investigation and resource control optimization is necessary for effective disease prevention and health management. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/3673 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/3673/1286