MOLECULAR CHARACTERIZATION OF FISH-BORNE TREMATODE METACERCARIAE INFECTING FRESHWATER FISH IN RICE FIELD OF CENTRAL THAILAND

Saiwasan Buathong1, Bonnie Lee Webster2, Saovanee Leelayoova3, Mathirut Mungthin3, Toon Ruang-areerate3,Tawee Naaglor3, Paanjit Taamasri3, Picha Suwannahitatorn3, Sommai Janekitkarn4 and Peerapan Tan-ariya1

Abstract

Fish-borne trematode (FBT) infection is the major parasitic infection in Asia. In Thailand, a high prevalence of FBT infection in humans has been reported in the north and northeast regions; however, there is no study on the distribu-tion and prevalence of FBT infection in the central part of the country. Hence, we identified trematode metacercariae in freshwater fish from central Thailand. From rice fields of three villages in a rural area of central Thailand, 218 freshwater fish were morphologically identified and their tissues digested to isolate metacercariae. Morphologically identical metacercariae from each fish were pooled in groups of 2-3 and their species and phylogenetic relationships were determined using DNA sequences of nuclear ITS2 and mitochondrial cox1. Eleven fish were infected with, in all, 60 metacercariae and from 20 pooled samples, fish from Na Ngam Village were found to be infected with metacercariae closely related to Haplorchis taichui and two unidentified genotypes, and fish from Na Yao Village were infected with NayaoMeta1 (12 metacercariae) and NayaoMeta2 (17 metacercariae). More stud-ies on the prevalence of these infections are required to assess whether the FBT infections have an impact on human health in these areas of Thailand.