Exposure to Crimean-Congo Hemorrhagic Fever Virus in Wild Ungulates in the Basque Country, Northern Iberian Peninsula.

Crimean-Congo hemorrhagic fever virus (CCHFV) causes a serious human tick-borne disease. In animals, CCHFV infections are mainly subclinical. The circulation of the virus has received little attention in areas where the main vector (Hyalomma spp.) is not considered to be present or established (e.g., the Northern Iberian Peninsula). The presence of antibodies against CCHFV was evaluated in sera collected from 1190 wild boars, 36 red deer, and 36 roe deer in the Basque Country (Northern Iberian Peninsula) in 2014-2019. Antibodies were found in the three wild ungulate species with an overall prevalence of 2.5%. The highest seroprevalence was found in red deer (22.2%) and in the southwest province: Araba (8.6%). The presence of antibodies against CCHFV in wild ungulates reported in this study could be due to an underestimated presence of Hyalomma ticks, the sporadic exposure to infected Hyalomma ticks transported by animals (e.g., migratory birds), or the role of other tick species in the virus's circulation. The detection of exposed animals since 2014 suggests that the circulation of the virus beyond the southwestern regions of the Iberian Peninsula could have been more widespread than previously thought.