A Study into the Identity, Patterns of Infection and Potential Pathological Effects of Rumen Fluke and the Frequency of Co-Infections with Liver Fluke in Cattle and Sheep

Abstract

Rumen fluke (RF) are trematode parasites that have increased in prevalence within European ruminant livestock since the 1990s. Morbidity and mortality can result from the development of juvenile flukes in the duodenum, however, evidence for significant impacts of adult fluke in the rumen of the final host is equivocal. The presence of rumen fluke in Scotland had not previously been quantified, so the purpose of this study was to use historical coprological data collected between 2008 and 2018 at the School of Veterinary Medicine in Glasgow to evaluate the frequency of rumen fluke infection and to compare this with the presence of liver fluke. This analysis showed evidence of adult rumen fluke in 6.6% of samples submitted, with a substantial and significant increase in positive diagnoses from 2016, following which positive rumen fluke diagnoses equaled or slightly outnumbered those of liver fluke. A prospective post-mortem examination study was also carried out to determine the presence of rumen and liver fluke in cattle and sheep, to quantify adult rumen fluke burdens and to assess any pathological changes in the reticulorumen and proximal duodenum associated with infection. The presence of rumen fluke in post-mortem cases was 26.9% (n = 18/67), the majority (66.7%, n = 12/18) with burdens of less than 100 adult rumen flukes. There was no significant difference in mean ruminal papillar density and length in animals with and without adult rumen fluke and no significant gross pathology was observed in the rumen or reticulum. Examination of animals with adult rumen fluke provided no evidence of any consistent associations with acute or chronic inflammatory changes in the duodenum. All rumen fluke collected at necropsy were identified by PCR and sequencing as Calicophoron daubneyi.