Seroprevalence of Leptospirosis, Brucellosis, and Q Fever in a Wild Red Deer (Cervus elaphus) Population Kept in a Fenced Reserve in Absence of Contact with Livestock.

Wildlife health is of interest for public and animal health because wild animals have been identified as important sentinels for the surveillance for zoonotic pathogens. This work investigated Brucella spp., Coxiella burnetii, and Leptospira spp. infection seroprevalence in a free-ranging red deer population. The study was conducted in a fenced reserve with controlled hunting activity in central Spain with animals that did not have any contact with livestock. Sampling was performed at two time points before and 5 years after the implementation of new management measures, including a reduction in the red deer population in the reserve. In addition, the presence of Leptospira DNA was tested in placental and fetal samples from seropositive pregnant animals. Antibodies against Brucella and Coxiella were not detected in any sample. The seroprevalence of Leptospira was 9.4% (13/137) in the first sampling for serovars Canicola and Panama. Five years later, the prevalence rose to 38.5% (97/252) with Pomona, the only serovar detected. Animals older than 2 years (50%; 70/140) were more likely to be Pomona seropositive than animals ≤2 years old (25.2%; 27/107; p < 0.001). Leptospira DNA was not detected in any sample tested. In conclusion, wild red deer in this area without contact with livestock seem not to play an important role in Brucella spp. and C. burnetii maintenance. The high seroprevalence of Leptospira spp. serogroup Pomona could indicate a risk for people with narrow contact with these animals, but the carrier status was not assessed. Consequently, it is unknown if red deer would represent a risk for human infection. Considering that wild boar could be the source of infection to red deer, the role of wild boar in the spread of leptospirosis and the risk for human infection should be investigated.