Novel insights into the pathogenic importance, diagnosis and treatment of the rumen fluke (Calicophoron daubneyi) in cattle.

Recently, sharp increases in the prevalence of rumen fluke infections have been recorded throughout Western Europe. However, scarce information is available on the diagnosis, pathogenic importance and control of this parasite. We undertook 3 pilot studies to gain more insights into these aspects of rumen fluke biology in cattle. First, we evaluated the diagnostic performance of mini-FLOTAC to detect adult rumen fluke infections based on faecal egg count in an abattoir survey and found high sensitivity (0.94) and specificity (0.98). Moreover, there was an association between ruminal fluke burden (assessed by visual scoring) and faecal egg count and a cut-off of 200 eggs per gram is proposed to detect highly infected animals (>200 flukes present in the rumen and/or reticulum). There was also a significant association between ruminal fluke burden and faecal consistency. However, in a second study, we performed a case-control field survey to investigate the association between rumen fluke infection and herd-level problems with diarrhoea and no association was found. Finally, we evaluated the use of closantel (Flukiver(®), Elanco Animal Health, subcutaneous administration at 10mg/kg) to treat rumen fluke infection on 3 herds, but no significant reduction in egg output post-treatment was found. Because this result is in contrast with a previous study using an oral dose of closantel, more research is required into the effect of administration route on the efficacy of closantel on rumen fluke.