Morphological and molecular characterization of Eurytrema spp. Looss, 1907 detected in domestic water buffaloes and cattle in northern Vietnam

Eurytrema spp. are pancreatic flukes belonging to the Dicrocoeliidae family. They are the cause of neglected diseases in Vietnam and are responsible for economic losses in ruminant production, particularly in water buffaloes and cattle. Eurytrema spp. have been widely reported in several Asian countries. Recently, morphological and molecular analyses to discriminate Eurytrema spp. have been conducted in Brazil, China, Bangladesh, Nepal, and Indonesia; however, similar analyses have not been performed in Vietnam. In the present study, we identified Eurytrema flukes collected from water buffaloes and cattle in northern Vietnam based on their morphology. Morphometric analyses were conducted on 15 samples each of Eurytrema cladorchis and Eurytrema coelomaticum. Representative samples from both species were selected for molecular analyses, and the nucleotide sequences of the 18S ribosomal RNA (18S rRNA) gene and internal transcribed spacer 2 (ITS2) were determined. Phylogenetic analyses based on 18S rRNA sequences revealed that E. cladorchis from Vietnam belongs to the same clade as that from Bangladesh. Similarly, E. coelomaticum isolates from Vietnam and China belonged to the same clade. Both clades were isolated from E. pancreaticum. This is the first study to describe the coexistence of E. cladorchis and E. coelomaticum in Vietnam and the first report of the ITS2 nucleotide sequence for E. coelomaticum, which can be used for molecular species discrimination.