High prevalence of natural infection by the ruminant blood fluke in the intermediate snail host in Uttaradit, Northern Thailand.

BACKGROUND AND AIM

Freshwater snails belonging to the family serve as the first intermediate hosts of many species of important parasitic flukes of animals and humans. Information regarding the occurrence of planorbid snail larval trematode infection is limited in Northern Thailand. Thus, this study aimed to estimate the prevalence of larval trematode infection of the freshwater snail in Uttaradit, Thailand, and to identify trematode species based on their morphological and molecular characteristics.

MATERIALS AND METHODS

Planorbid snail specimens were collected from a water reservoir in Uttaradit, Thailand, from June to August 2023. Snails were assessed for larval trematode infection through cercarial shedding and crushing methods. The released cercariae were preliminarily identified on the basis of their morphological characteristics. In addition, species identification of the detected cercariae was conducted using 28S ribosomal RNA and cytochrome c oxidase subunit 1 gene sequence analyses.

RESULTS

The overall prevalence of cercarial infection was 61.5% (107/174) in planorbid snails in Uttaradit province. Two species of cercarial trematodes, (106/174, 60.9%) and (1/174, 0.6%), were identified using morphological and molecular analyses, of which was the most abundant species. Our studied snails did not have mixed infection with more than two cercarial species.

CONCLUSION

Our findings reveal a remarkably high prevalence of cercariae infecting planorbid snails in Uttaradit, indicating that humans and animals across the study area are at risk of infection. Our data may contribute to the development of effective strategies to control this zoonotic infectious disease.