Abstract
Brackish water snail is one of the important intermediate hosts of trematode infections. This kind of snail along the Gulf of Thailand were examined for cercariae, the larval stage of trematodes. The aim of this study was to investigate cercarial infections in brackish water snails in the central and eastern side of the Gulf of Thailand. Snails were collected from 45 sampling sites (20 central areas, 25 eastern areas), between August 2013 and February 2014. A total of 8,532 snails were classified into 12 families, 23 genera and 32 species. Cercarial infections were investigated using shedding and crushing methods. The infection rate was 0.27% (23/8,532). The cercariae were categorized into 5 types and 8 species. The first type, Parapleurophocercous cercariae, consisted of Haplorchis taichui, Heterophyes cercaria I, and Metorchis intermedius. The second type, Xiphidiocercariae, consisted of Ascorhytis charadriformis. The third type, Furcocercous cercariae, consisted of Apharyngostrigea pipientis. The forth type, Cotylomicrocercous cercariae, consisted of Coitocaecum anaspidis. The fifth type, Echinostome cercariae, consisted of Hypoderaeum conoideam and Himasthla interrupta. Seven species of snails were found with trematode infections, comprising of Assiminea brevicula, Cerithidea cingulata, Cerithidea alata, Cerithidea djadjariensis, Cerithidea quadrata, Littorinopsis intermedia, and Sermyla riqueti.
Key words: Cercaria, brackish water snails, trematode, the Gulf of Thailand.
