Eurytrema coelomaticum: updated morphology of adult worms using advanced microscopy experiments

Form and Function in the Digenea, with an Emphasis on Host-Parasite and Parasite-Bacteria Interactions

This review covers the general aspects of the anatomy and physiology of the major body systems in digenetic trematodes, with an emphasis on new knowledge of the area acquired since the publication of the second edition of this book in 2019. In addition to reporting on key recent advances in the morphology and physiology of tegumentary, sensory, neuromuscular, digestive, excretory, and reproductive systems, and their roles in host-parasite interactions, this edition includes a section discussing the known and putative roles of bacteria in digenean biology and physiology. Furthermore, a brief discussion of current trends in the development of novel treatment and control strategies based on a better understanding of the trematode body systems and associated bacteria is provided.

Characterization of the Complete Mitochondrial Genome and Phylogenetic Analyses of Eurytrema coelomaticum (Trematoda: Dicrocoeliidae)

Eurytrema coelomaticum, a pancreatic fluke, is recognized as a causative agent of substantial economic losses in ruminants. This infection, commonly referred to as eurytrematosis, is a significant concern due to its detrimental impact on livestock production. However, there is a paucity of knowledge regarding the mitochondrial genome of E. coelomaticum. In this study, we performed the initial sequencing of the complete mitochondrial genome of E. coelomaticum. Our findings unveiled that the mitochondrial genome of E. coelomaticum spans a length of 15,831 bp and consists of 12 protein-coding genes, 22 tRNA genes, two rRNA genes, and two noncoding regions. The A+T content constituted 62.49% of the genome. Moreover, all 12 protein-coding genes of E. coelomaticum exhibit the same arrangement as those of E. pancreaticum and other published species belonging to the family Dicrocoeliidae. The presence of a short string of additional amino acids (approximately 20~23 aa) at the N-terminal of the cox1 protein in both E. coelomaticum and E. pancreaticum mitochondrial genomes has contributed to the elongation of the cox1 gene in genus Eurytrema, surpassing that of all previously sequenced Dicrocoeliidae. The phylogenetic analysis displayed a close relationship between E. coelomaticum and E. pancreaticum, along with a genus-level association between Eurytrema and Lyperosomum. These findings underscore the importance of mitochondrial genomic data for comparative studies of Dicrocoeliidae and even Digenea, offering valuable DNA markers for future investigations in the systematic, epidemiological, and population genetic studies of this parasite and other digenean trematodes.

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.

Pancreatic eurytrematosis in small ruminants: A forgotten disease or an untold history?

Trematodiosis are among the most neglected parasitic diseases worldwide. The pancreatic eurytrematosis (PE) is a chronic parasitic infection mostly reported in cattle but has been unnoticed in small ruminants for many decades. Our review showed PE has been recorded as scattered regional reports in goats and sheep, mainly in Asia and Eastern Europe. Eurytrema coelomaticum, Eurytrema cladorchis, and Eurytrema pancreaticum have been the main pathogenic species infecting pancreatic ducts of small ruminants. Climatic, environmental, and regional conditions in both hemispheres may support the survival and feasibility of intermediate hosts and parasitic forms, enabling the emergence and spread of PE in small ruminants. As a primarily asymptomatic condition, PE in goats and sheep flocks may also have a high prevalence, causing severe parasitic pancreatitis, production losses, and death. There is little information on anthelmintic therapeutics for PE in small ruminants, and most used anti-fluke drugs are ineffective. PE is likely more unnoticed than a neglected trematodiosis in goats and sheep, or both from a global perspective.

Comparison of two coprological methods for the diagnosis of Eurytrema ssp. in cattle and sheep

Eurytrematosis is a disease caused by flukes of the genus Eurytrema. These parasites infect the pancreatic ducts of a wide variety of species, including cattle, sheep and humans. Diagnosing eurytrematosis through the analysis of faecal samples can be difficult because most of the available techniques are considered of low sensitivity. In this context, a modification of the Dennis, Stone and Swanson technique (Belem Sedimentation Technique, BST) was previously developed to increase the probability of detecting infected animals; nevertheless, the values of eggs per gram obtained using the modified technique are generally low. We proposed a modification of the this technique (MBST), to increase the sensitivity and detection rate of infected animals. The objective of this work was to describe MBST and compare it with BST. Faecal samples of 212 clinically healthy animals (174 from cattle and 38 from sheep) from 20 farms were taken by the intra-rectal route and stored at 4°C. The samples were processed using BST and MBST. Positive samples amounted to 55 (25.9%) using BST and 121 (57.1%) using MBST. In the simples from cattle, 52 (29.8%) and 107 (61.4%) were positive in BST and MBST, respectively. In sheep, three (7.8%) and 14 (36.8%) positive samples were obtained in BST and MBST, respectively.The results obtained using the two methods were significantly different, indicating a lack of agreement between their findings. The results suggest that MBST is a more sensitive method to detect Eurytrema spp. eggs in faeces than BST.

Eurytrema coelomaticum natural infection in small ruminants: a neglected condition

Pancreatic eurytrematosis (PE) is an under diagnosed and neglected parasitosis in goats and sheep in the Americas. Clinical and pathological features of PE are not well defined in small ruminants worldwide. Natural cases of PE in small ruminants were detected in the Federal District, Brazil. A survey of necropsy records, including epidemiological and clinicopathological data, in goats and sheep was conducted. Most cases of PE occurred during the rainy season in adult females, with an incidence of 12.9% in goats and 0.8% in sheep. Clinical signs varied from asymptomatic infections to anorexia, lethargy, weakness, marked weight loss and death in some goats. Overall, most cases of PE in goats and sheep were incidental necropsy findings with minor pancreatic lesions. Three goats, however, showed severe chronic pancreatitis, dilation of major pancreatic ducts with numerous trematodes present and marked abdominal fat necrosis. Morphological and molecular characterization of flukes detected Eurytrema coelomaticum. Our findings shed light on the prevalence of E. coelomaticum infections in small ruminants in the region and highlight the possibility of severe and lethal cases in goats. PE must be further investigated in small ruminant populations in relevant livestock production regions of the Americas.