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Cercarial trematodes in freshwater snails from Bangkok, Thailand: prevalence, morphological and molecular studies and human parasite perspective

Published online by Cambridge University Press:  26 October 2020

Pichit Wiroonpan
Affiliation:
Animal Systematics and Ecology Speciality Research Unit, Department of Zoology, Faculty of Science, Kasetsart University, Bang Khen Campus, Bangkok, 10900, Thailand
Thapana Chontananarth
Affiliation:
Applied Parasitology Research Laboratory, Department of Biology, Faculty of Science, Srinakharinwirot University, Bangkok, Thailand Center of Excellence in Animal, Plant and Parasitic Biotechnology, Srinakharinwirot University, Bangkok, Thailand
Watchariya Purivirojkul*
Affiliation:
Animal Systematics and Ecology Speciality Research Unit, Department of Zoology, Faculty of Science, Kasetsart University, Bang Khen Campus, Bangkok, 10900, Thailand
*
Author for correspondence: Watchariya Purivirojkul, E-mail: [email protected]

Abstract

We investigated the prevalence, morphological characters and molecular classifications of trematode cercariae in freshwater snails randomly collected from 59 sampling localities in Bangkok from May 2018 to March 2019. We used a crushing technique to observe the cercarial stage inside each snail body and amplified the internal transcribed spacer 2 regions of cercarial DNA using polymerase chain reaction methodology. The associated phylogenetic tree was reconstructed using Bayesian inference analyses. A total of 517 of 15 621 examined snails were infected with trematode cercariae, and the infected snails were classified into 11 species of seven families with a 3.31% overall prevalence of the infection. The Bithynia siamensis siamensis snail displayed the highest prevalence of infection (16.16%), whereas the Physella acuta snail exhibited the lowest prevalence (0.08%) of infection. Eight morphological types of cercariae were observed. The highest prevalence of infection was observed in mutabile cercaria (1.86%). Based on molecular investigations, the phylogram revealed eight cercaria types assigned to at least nine digenean trematode families, of which five belong to groups of human intestinal flukes. Although, with the exception of schistosome cercaria, trematode cercariae are not known to directly damage humans, understanding the general biology of trematode cercariae (including diversity, distribution, infection rates and host range) is important and necessary for the prevention and control of parasitic transmission that impacts aquatic cultivations, livestock farming and human health.

Type
Research Article
Copyright
Copyright © The Author(s), 2020. Published by Cambridge University Press

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