Morphological and molecular characterization of Eurytrema coelomaticum found in bovine pancreas in Argentina

Eurytrema spp. flukes are responsible for economic losses in ruminant production, leading to hyperplasia and hypertrophy of the bile ducts, periductal fibrosis and loss of pancreatic parenchyma. These flukes affect ruminants, small carnivores and occasionally humans. The aim of this study was to perform a precise identification by morphometry and molecular markers in Eurytrema flukes from Argentina, also clarify their phylogenetic relationships. Eurytrema flukes were collected from the pancreatic ducts of breed cattle examined during necropsies in Montecarlo, Misiones province, Argentina. Precise identification of species of the genus Eurytrema is important because some of them can affect humans. Reports of Eurytrema species have in Argentina, Brazil and several Asian countries. In this study, we identified 20 Eurytrema flukes as Eurytrema coelomaticum by morphological characters, collected from Montecarlo. Four individuals were selected for molecular analyses targeted to 18S rRNA and ITS2 genes, with sequence analyses conducted to confirm identification due to the conflicting morphological classification among Eurytrema species. For both genes, we performed multiple alignments with reference sequences, constructed phylogenetic trees and realized an analysis of genetic divergence, based on a pairwise comparison. Phylogenetic analyses based on 18S rRNA sequences revealed that E. coelomaticum from Argentina shows high similarity with sequences from Brazil with low percent of 18S rRNA gene divergence, forming a separate group from E. coelomaticum found in China and Vietnam, no sequence variation was observed among this Asian E. coelomaticum isolates. This indicates there is evolutionary divergence between E. coelomaticum from South America and Asia. This study presents, for the first time, the sequence of the ITS2 gene for E. coelomaticum from South America, which showed 100% similarity with E. coelomaticum isolated from Vietnam. Findings confirmed that E. coelomaticum is circulating in Argentina, as the presence of E. pancreaticum poses a potential public health risk due to its zoonotic potential. Continued monitoring of Eurytrema species in the country is essential through epidemiological and molecular surveillance.