Infections of Digenetic Trematode Metacercariae in Wrestling Halfbeak, Dermogenys pusilla from Bangkok Metropolitan Region in Thailand

Abstract

This study aimed to investigate metacercarial infections in the wrestling halfbeak, <i>Dermogenys pusilla</i>, collected from Bangkok metropolitan region of Thailand. A total of 4,501 fish from 78 study sites were commonly examined with muscle compression and digestion methods (only head part of fish) during September 2017 to July 2018. The overall prevalence of metacercarial infection was 86.1% (3,876/4,501 individuals), and the mean intensity was 48.9 metacercariae per fish infected. Four species, i.e., <i>Posthodiplostomum</i> sp., <i>Stellantchasmus falcatus</i>, Cyathocotylidae fam. sp., and <i>Centrocestus formosanus</i>, of digenetic trematode metacercariae (DTM) were detected. The prevalences were 65.8%, 52.0%, 2.1%, and 1.2%, respectively and their mean intensities were 23.1, 51.6, 1.4, and 3.2 per fish infected, respectively. The seasonal prevalences were 81.0% in winter, 87.8% in summer and 87.4% in rainy, and the mean intensities were 38.9, 46.6, and 55.2 metacercariae per fish infected, respectively. Conclusively, it was confirmed that the wrestling halfbeak play the role of second intermediate hosts of 4 species of digenetic trematodes including <i>S. falcatus</i> and <i>Posthodiplostomum</i> sp. in Bangkok metropolitan region. And then the metacercariae of <i>C. formosanus</i> and Cyathocotylidae fam. sp. are to be first found in the wrestling halfbeak by this study.