Animal Health and Infectious Diseases

Animal Health and Infectious Diseases

Molecular Identification and Phylogenetic Analysis of Pleurogenoides medians (Digenea: Pleurogenidae) Cercariae Isolated from the Freshwater Snail Bithynia tentaculata (Gastropoda: Bithyniidae) in Deh Sefid Village, Khorramabad County, Lorestan Provi

Document Type : Original Article

Authors
Faezeh Salavati 1
Hassan Nayebzadeh 1
Asadollah Hosseini Chegeni 2
Narges Nazifi 3
Yasin Valizadeh 4
1 Department of Pathobiology, Faculty of Veterinary Medicine, Lorestan University, Khorramabad, Iran
2 Department of Plant Protection, Faculty of Agriculture, Lorestan University, Khorramabad, Iran
3 Lorestan University, Veterinary Faculty, Department of Basic Science, Khorramabad, Lorestan
4 Lorestan University, Veterinary Faculty, Department of Clinical Sciences, Khorramabad, Lorestan
10.22034/jahid.2026.2090644.1071
Abstract
Introduction: Digenean trematodes are among the most important parasites with complex life cycles, in which the cercarial stage plays a decisive role in disease transmission. Freshwater snails, particularly Bithynia tentaculata, are recognized as the first intermediate hosts of many trematodes, and their wide distribution in western and central Iran highlights the need for investigating associated parasitic infections. Given the difficulty of species-level identification of cercariae based solely on morphological characteristics, this study aimed to investigate trematode infection in B. tentaculata and to identify the isolated species using molecular methods in the Khorramabad region.
Materials and Methods: Snails were collected from natural habitats, and trematode cercariae were isolated from them. After DNA extraction, the parasite 28S rRNA gene was amplified by PCR, and the resulting products were sequenced.
Results: BLAST analysis revealed that the examined cercariae showed the highest genetic similarity to Pleurogenoides medians (family Pleurogenidae). Phylogenetic analysis further confirmed this finding, as the study samples clustered within the species-specific clade of P. medians.
Conclusion: The identification of P. medians in B. tentaculata represents the first molecular report of this species in Iran and the first record of its occurrence in a first intermediate host in the country. Previous reports of this trematode have mainly been from definitive hosts, particularly amphibians. These findings not only expand the known geographical range and host spectrum of P. medians but also emphasize the importance of assessing larval trematodes in freshwater snails and their potential role in the transmission cycles of pathogenic parasites in Lorestan Province. The results of this study provide a basis for future research on parasite epidemiology, ecology, and the assessment of environmental risks associated with larval trematodes in Iranian freshwater ecosystems.
Keywords
Pleurogenoides medians
Bithynia tentaculata
Cercaria
28S rRNA
Molecular identification
Subjects
.1 Cribb TH, Bray RA, Olson PD, Littlewood DT. Life cycle evolution in the digenea: a new perspective from phylogeny. Adv Parasitol. 2003;54:197–254. doi:10.1016/s0065–308x(03)54004– 0.
.2 Cribb TH, anderson GR, Adlard RD, Bray RA. A DNA-based demonstration of a three-host lifecycle for the Bivesiculidae (Platyhelminthes: Digenea). Int J Parasitol. 1998;28(11):1791–5. doi:10.016/S0020–7519(98)00127–1 .
.3 Galaktionov KV, Dobrovolskij A. The biology and evolution of trematodes: an essay on the biology, morphology, life cycles, transmissions, and evolution of digenetic trematodes: Springer Science & Business Media; 2013.
.4 Modabbernia G, Meshgi B, Rokni MB. A faunistic survey of snails and their infection with digenean trematode cercariae in Bandar-e Anzali at the littoral of the Caspian Sea. Ann Parasitol. 2021;67(4):703–13. doi:10.17420/ap6704.387 .
.5 Razi Jalali MH, Mirzaei M, Jahangiri Nasr F, Sharifi H. Identification and Determination of the Geographical Distribution of Freshwater Snails in Lorestan ,Iran. Arch Razi Inst. 2019;74(4):423–31. doi:10.22092/ari.2018.123286.1244 .
.6 Glöer P, Pešić V. The freshwater snails (Gastropoda) of Iran, with descriptions of two new genera and eight new species. ZooKeys. 2012(219):doi:10.3897/zookeys.219.406 .
.7 Schwelm J, Kudlai O, Smit N, Selbach C, Sures B. High parasite diversity in a neglected host: larval trematodes of Bithynia tentaculata in Central Europe. J Helminthol. 2020;94:e120. doi:10.1017/S0022149X19001093 
8 Serbina E. Larval trematodes in bithyniid snails (Gastropoda: Bithyniidae) in the lake-rivers systems from the steppe zone (The West Siberian Plain, Russia). Helminthologia. 2014;51(4):293–300. doi:10.2478/s11687–014–0244–5 .
.9 Malek EA. Snail transmitted parasiticdiseases: Volume I. New York USA: CRC press; 1980. 334 p .
 .10 Bawm S, Khaing NHE, Win SY, Thein SS, Khaing Y, Thaw YN, et al. Morphological and molecular identification of trematode cercariae related with humans and animal health in freshwater snails from a lake and a dam in Myanmar. Parasitol Res. 2022;121(2):653–65. doi:10.1007/s00436–022–7428– 4.
 .11 Pitaksakulrat O, Sithithaworn P, Kopolrat K, Kiatsopit N, Saijuntha W, Andrews R, et al. Molecular identification of trematode parasites infecting the freshwater snail Bithynia siamensis goniomphalos in Thailand. J Helminthol. 2022;96:e49. doi:10.1017/S0022149X22000402 .
 .12 Chaudhary A, Shinad K, Prasadan PK, Singh HS. Phylogenetic Position of Pleurogenoides Species (Plagiorchiida: Pleurogenidae) from the Duodenum of Indian Skipper Frog ,Euphlyctis Cyanophlyctis (Amphibia: Dicroglossidae) Inhabiting the Western Ghats, India. Helminthologia. 2020;57(1):71–7 .
 .13 Gao J-F, Ma T-S, Hou M-R, An Q, Liu X-W, Zhang X-H, et al. Characterization of the Complete Mitochondrial Genome of Pleurogenoides japonicus (Digenea, Pleurogenidae): Comparison With the Members of Microphalloidea and Phylogenetic Implications. Ecology and Evolution. 2024;14(10):e70430 .
 .14 Maleki L, Shahmoradi M, Golzarianpour K. PARAPLEUROGENOIDES (DIGENEA), A NEW GENUS IN PELOPHYLAX BEDRIAGAE (ANURA: RANIDAE) FROM KURDISTAN, IRAN WITH COMMENTS ON THE RELATIONSHIPS WITHIN PLEUROGENIDAE. J Parasitol. 2025;111(4):431–40 .
 .15 Mashaii N, Balouch M, Moubedi I. New records about helminth parasites of the marsh frog, Rana ridibunda ridibunda (Anura: Ranidae) from the north of Iran. Iranian J Fish Sci. 2000;2(2):77–88. doi:10.18869/acadpub.ijfs .
 .16 Salahi-Moghaddam A. Medical malacology for student of health sciences. Hormozgan Iran: Hormozgan University of Medical Sciences - Rasul Publications; 2013. 253 [In Persian] p .
 .17 Kim JJ. Radula Tooth Structure of Eight Bithyniid Snails Observed by Scanning Electron Microscopy. 한국패류학회지. 2015;31(1):49–59 .
 .18 Chaudhary A, Shinad K, Prasadan PK, Singh HS. Phylogenetic Position of Pleurogenoides Species (Plagiorchiida: Pleurogenidae) from the Duodenum of Indian Skipper Frog, Euphlyctis Cyanophlyctis (Amphibia: Dicroglossidae) Inhabiting the Western Ghats, India. Helminthologia. 2020;57(1):71–7. doi:10.2478/helm–020–0006 
Animal Health and Infectious Diseases
Volume 3, Issue 1
June 2026
Pages 93-97