Beyond stabilization: prevalence, risk factor 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 coprological 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 paramphistomids in cattle from Spain. Prevalence was significantly influenced by region (Asturias: OR 11.4), age (> 60 months: OR 17.1; 25–60 months: OR 5.8), co-infection with Fasciola hepatica (OR 13.1) and absence of slurry scrapers (OR 76.9). 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. Molecular analysis confirmed Calicophoron daubneyi as the most common species. 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 the urgent need for targeted surveillance, farmer education, and integrated control measures in north-western Spain, especially in Asturias, where infection rates are particularly high.