Observations on the biology, epidemiology and economic relevance of rumen flukes (Paramphistomidae) in cattle kept in a temperate environment.

There is concern about the probable recent introduction, increased prevalence and potential economic impact of rumen fluke infection of United Kingdom cattle. A study of 339 cattle slaughtered in a Scottish red meat abattoir was undertaken with the aims of describing the prevalence and geographical distribution of rumen fluke infection, estimating its effect on production, and evaluating faecal egg counts (FECs) as a tool to diagnose infection in live animals and study the epidemiology of the disease. The overall proportion of cattle consigned to the abattoir from northern United Kingdom with rumen fluke infection in the forestomachs was 0.29. Rumen flukes were distributed predominantly in the cranial sac of the rumen and adjacent to the reticular groove. Overall, a mean of 213 and median of 44 rumen flukes was identified in the forestomachs of rumen fluke-positive cattle. The mean and median FECs of animals were 26.01 and 5.20 eggs per gram (epg), respectively. There was a significant difference between the mean FECs per rumen fluke of 0.08 and 0.13 epg during summer/autumn and winter sampling periods, respectively. The overall correlation between rumen fluke FECs and the number of flukes in the forestomach was high, albeit lower in the summer/autumn than in the winter period. The sensitivities of rumen fluke FECs for the identification of flukes in the forestomach during the summer/autumn and winter sampling periods were 0.65 and 0.85, respectively. These results will aid in the interpretation of rumen fluke FECs when monitoring cattle health and production and studying the parasite's epidemiology in a temperate environment, thereby informing rational, precise and sustainable disease control.