Bovine paramphistomes in Ireland

Abstract

Paramphistome infections have been associated with significant morbidity, caused chiefly by the activity of juvenile flukes in the intestine of the ruminant final host. Most cases have been reported in tropical and sub-tropical areas. However, recent reports of an apparent increase in the incidence of rumen fluke and its geographical range in Europe have renewed interest in a parasite previously thought to be of little significance in temperate regions. Moreover, the identity of rumen flukes present in the British Isles is currently being revised. As a result, work is underway throughout Europe to review and re-assess the clinical and economic significance of rumen flukes. During the present study, historical diagnostic laboratory records were interrogated for recent changes in the incidence of rumen fluke in Ireland. Three cattle herds were monitored for the presence of paramphistome eggs using coprological analysis over a period of 2 months (in the case of a group of housed steers) and 14 months (in the case of two extensively operated farms), respectively. Adult rumen fluke collected following slaughter were weighed and typed in two loci. We found that Calicophoron daubneyi is the most common if not only paramphistome species present in Ireland and that infections in cattle are now much more prevalent than was the case five or six years ago. The pylogenetic relationship of our isolates to the only published sequence and to C. daubneyi isolates from Northern Ireland was analysed. Genetic heterogeneity was similar all over the island and comparable to that of Fasciola hepatica, a fact that may have implications for the parasite's ability to develop resistance to the very limited number of drugs currently available for treatment. The same haplotypes predominated throughout the island. Although the clinical significance of C. daubneyi is still uncertain, considering the apparent pervasiveness of the parasite, rumen fluke should be considered a differential diagnosis when treating scour or ill-thrift in young calves, and goats and sheep of any age.

Keywords: Calicophoron daubneyi; Epidemiology; Faecal egg count; Network analysis; Paramphistomosis; Phylogenetic analysis.