Influence of livestock, habitat type, and density of roe deer (Capreolus capreolus) on parasitic larvae abundance and infection seroprevalence in wild populations of roe deer from central Iberian Peninsula

Livestock farming is a common human activity that not only modifies natural habitat but also may lead to interactions with other wild animal species. We studied whether health status of roe deer (Capreolus capreolus) is influenced by density, livestock, and type of habitat. We analyzed 208 samples (120 fecal and 88 sera) from roe deer populations of central Iberian Peninsula to evaluate both presence and abundance of parasitic oocysts, eggs, and/or larvae, especially of gastrointestinal and bronchopulmonary parasites, as well as the prevalence of five infectious diseases (infectious bovine rhinotracheitis (IBR), pestivirosis (BVD/BD), paratuberculosis (PTB), bluetongue (BT), and brucellosis). Fecal samples were collected in transects in pine and oak forests and endoparasites were detected by means of coprological techniques. Serum samples were obtained from hunted individuals and the serological testing for the infectious pathogens was performed by ELISA and Rose Bengal tests. Livestock and habitat type were associated both with the presence and the number of bronchopulmonary nematode L1-larvae per gram of feces (lpg), which was higher in areas with livestock and in pine forests. However, roe deer density neither influenced parasite presence nor lpg values. Regarding infectious pathogens, only seropositive samples for PTB and pestivirus were obtained indicating a possible transmission between domestic and wild ungulates in the study area. The low prevalence found is consistent with other studies in the Iberian Peninsula suggesting that roe deer have little contact with the infectious agents studied. Our results highlight that both habitat type and livestock significantly mediate abundance of parasitic larvae in roe deer, being higher under competition scenarios and in habitats of lower quality, a valuable aspect to be considered in future management and conservation strategies.