Beyond stabilization: prevalence, risk factors and molecular identification of rumen flukes in cattle from Northwestern Spain.

Background: An upward trend of paramphistomid prevalence was detected in domestic ruminants from Europe in the last decades. Nevertheless, recent data from Ireland, which reports the highest prevalences in Europe, suggests that this trend may be stabilizing. This study analysed the current epidemiological situation of rumen fluke infections in cattle from northwestern Spain, focusing on two regions: Galicia, where increasing prevalences were reported, and Asturias, where data is limited. Between 2018 and 2022, 3,095 faecal samples from 137 farms were analysed using sedimentation coproscopical technique. Risk factor analysis was conducted through mixed logistic regression and ANOVA; paramphistomid species were molecularly identified.

Results: High individual (51.2%; 95% CI: 49.4-53.0) and herd (81.8%; 95% CI: 74.1-87.6) prevalences were found, representing the highest recorded prevalence of paramphistomid infections in cattle from Spain. The risk of being infected significantly increased with age, being lower in cattle aged 1-24 months than in those 25-60 months-old (OR 5.8) or older than 60 months (OR 17.1). Prevalence was significantly higher in Asturias (OR 11.4) and in animals co-infected with Fasciola hepatica (OR 13.1). Animals from farms without slurry scrapers also showed significantly higher prevalences (OR 76.9), which may be related to less professionalization. Egg shedding intensity was notably higher in older animals and those co-infected with F. hepatica as well as in farms from coastal areas and using extensive management. Calicophoron daubneyi was the only species detected.

Conclusions: Our findings reveal a continued upward trend in rumen fluke prevalence in cattle from north-western Spain, suggesting that a stabilization of prevalence is not occurring. The study highlights that surveillance, farmer education, and integrated control measures are highly recommended in north-western Spain, especially in Asturias, where infection rates are particularly high.