Parasitological and molecular characterization of the avian schistosomatid cercariae infecting lymnaeidae snails in Phayao, Northern Thailand

Ornampai Japa; Chittakun Suwancharoen; Thanakon Bunsong; Chorpaka Phuangsri

doi:10.14202/vetworld.2021.2655-2661

Parasitological and molecular characterization of the avian schistosomatid cercariae infecting lymnaeidae snails in Phayao, Northern Thailand

Vet World. 2021 Oct;14(10):2655-2661. doi: 10.14202/vetworld.2021.2655-2661. Epub 2021 Oct 20.

Authors

Ornampai Japa^{1

2}, Chittakun Suwancharoen¹, Thanakon Bunsong¹, Chorpaka Phuangsri¹

Affiliations

¹ Division of Microbiology and Parasitology, School of Medical Sciences, University of Phayao, Thailand.
² Scientific Instrument and Product Standard Quality Inspection Center, University of Phayao, Thailand.

Abstract

Background and aim: Cercarial dermatitis or swimmer's itch is an allergic skin reaction caused by penetrating cercaria of animal blood flukes. It is considered as a zoonotic water-borne skin condition that is found globally. Among the schistosomatid trematodes, avian schistosomes are the most responsible for cercarial dermatitis. Very little is known regarding the occurrence of dermatitis-causing cercariae in Thailand. Therefore, the objective of this study was to preliminarily investigate the presence of larval blood fluke infection among local lymnaeidae snails in Phayao by the incorporation of morphological and molecular methods.

Materials and methods: Overall 500 Radix (Lymnaea) rubiginosa (Michelin, 1831) were collected from freshwater reservoirs near Phayao Lake in San Kwan village in Phayao, Thailand, from October to December 2020. The snails were examined for avian blood fluke infection by the cercarial shedding technique followed by morphological and molecular characterization.

Results: Only one type of furcocercous cercaria was observed to emerge from six infected snails (1.2%). Our molecular analyses demonstrated that the emerging cercariae showed most similarity to either the 28S ribosomal RNA gene (28S rDNA) or cytochrome oxidase C subunit 1 gene (cox1 or COI) sequences to those of Trichobilharzia species. In addition, phylogenetic tree analyses of both loci revealed similar results; the emerging cercariae were consistently clustered together with Trichobilharzia regenti.

Conclusion: Our results clearly confirmed that the detected furcocercous cercariae belonged to the genus Trichobilharzia and displayed the highest homology to T. regenti. This study provides important data on the occurrence of dermatitis causing cercariae infection among local lymnaeidae snails, encouraging effective management, and control measures for this zoonotic infectious disease.

Keywords: Radix (Lymnaea) rubiginosa; Trichobilharzia regenti; avian schistosome; cercarial dermatitis; furcocercous cercaria; swimmer’s itch.