Kitja Apiraksena. Morphological characterization and genetic identification of cercariae from infected snails intermediate host, genus Stenomelania Fischer, 1885 in Thailand.. Doctoral Degree(Biology). มหาวิทยาลัยศิลปากร. สำนักหอสมุดกลาง. : Silpakorn University, 2021.
Morphological characterization and genetic identification of cercariae from infected snails intermediate host, genus Stenomelania Fischer, 1885 in Thailand.
Abstract:
Stenomelania (Fischer, 1885) is one of the snail species in the family Thiaridae. It has been realized that the snail in this family played an important role as an intermediate host of human and animal trematodes. The objective of this study was to investigate the trematode infections, identification of cercarial species and distribution of snail genus Stenomelania spp. in Thailand. Snail samples were collected from 24 localities between 2017 and 2020 by hand picking and scooping methods. The snails were transferred and studied in the laboratory of the Parasitology and Medical Malacology Research Unit, Silpakorn University, Nakhon Pathom, Thailand. The snails were identified according to their shell morphology and confirmed with molecular genetics by using the CO1 gene marker. A total of 3,026 Stenomelania snails were classified into six species consist of S. cf. aspirans, S. cf. crenulata, Stenomelania sp., S. cf. punctata, S. cf. torulosa, and S. cf. denisoniensis. The shells were conical in shape and varied in length and width. They were found in short and tall shells, as slender and wide shapes, smooth or rib. The collected snails were investigated the trematode infections by shedding and crushing methods. The infection rate was found to be 0.63 %. The emerging cercariae were described as the morphology based on living cercariae which were unstained or vitally stained with 0.5% neutral red. They were categorized into a total of four species from morphologically, viz. Loxogenoides bicolor, Haplorchis taichui, Procerovum cheni and Acanthotrema tridactyla. In addition, a phylogenetic marker (ITS2) was employed in generic and infrageneric level classifications of these trematodes. This study represents both morphological characterization and genetic identification of cercariae, which could be recognized as the basis reference of the larval trematode fauna, and could predict their potential to evolve for intermediate snail hosts.