Looking for liver flukes: Dicrocoelium dendriticum infection in roe deer (Capreolus capreolus) from central Italy

Dicrocoelium dendriticum is a trematode that infects both domestic and wild animals, with transmission potentially occurring at the wildlife-domestic interface. This study aims to investigate liver fluke infection in roe deer (Capreolus capreolus) and its epidemiological role in central Italy, where the species coexists with domestic ruminants. A total of 265 roe deer livers were examined between 2021 and 2022 and animal data such as collection area, sex, age class, and seasonality were recorded. The livers were macroscopically examined to determine a Liver Lesion Score, and adult parasites were collected and counted. Overall, 52 of the 265 animals (19.6%) were infected by D. dendriticum flukes, identified through morphological and molecular methods. The total mean intensity of infection was 17.1 flukes per animal (ranging from 1 to 354). This study reports, for the first time, the presence of D. dendriticum in roe deer in Italy. The lower intensity of infection observed in roe deer compared to domestic animals in the literature may be related to the different dietary habits of these species. However, further studies are recommended to access (i) the potential role of roe deer as an animal in “refugia” and (ii) whether interactions between wild and domestic animals contribute to anthelmintic resistance in the latter.