Hotspot of Crimean-Congo Hemorrhagic Fever Virus Seropositivity in Wildlife, Northeastern Spain

C rimean-Congo hemorrhagic fever virus (CCH- FV) is an arthropodborne Orthonairovirus mainly transmitted by ticks.In humans, CCHFV infection can cause severe and even fatal Crimean-Congo hemorrhagic fever (CCHF) disease (1).CCHFV also can infect wild and domestic mammalian species, producing viremia but causing a predominantly asymptomatic disease and such species have a role in the maintenance of the virus in the environment (2).CCHFV is endemic in Africa, Asia, and eastern Europe but has more recently emerged in southwestern Europe.In 2010, CCHFV was detected in central-western Spain in Hyalomma lusitanicum ticks collected from red deer (Cervus elaphus) (3).In 2016, 2 autochthonous human CCHF cases were reported in Spain, 1 likely contracted through tick bite and the other caused by nosocomial transmission (4).Since then, 6 other CCHF clinical cases, including a retrospectively identifi ed case from 2013, have been reported in the country, all of which are suspected to be caused by infected ticks (5,6).Further surveys on ticks (7,8), and serologic studies in humans (9) and animals (10) have shown evidence of CCHFV circulation in several areas of central and southwestern Spain.The high genetic variability of the CCHFV strains identifi ed in Spain, including genotypes Africa III and IV and Europe V, are indicative of repeated introductions (7,8).The area of CCHFV detection coincides with the region where the ecologic conditions are more favorable for the presence of H. marginatum and H. lusitanicum ticks, the main vectors of the disease.Neither of these species have been reported in northeastern Spain, but ecologic models predict the existence of areas suitable for H. marginatum (11).To evaluate possible CCHFV circulation in Catalonia, northeastern Spain, we conducted a serosurvey to detect CCHFV antibodies in different susceptible wild animal species. The StudySerum samples from different wildlife species were collected during 2014-2020 as part of routine wildlife surveillance in Catalonia from areas representing different ecosystems (Figures 1, 2).We tested for CCHFV antibodies in serum samples from 174 red deer, 84 Iberian ibexes (Capra pyrenaica), 79 roe deer (Capreolus capreolus), 35 European rabbits (Oryctolagus cuniculus), 156 wild boars (Sus scrofa), and 4 fallow deer (Dama dama) (Table 1).We used the CCHF Double Antigen Multi-species ELISA kit (IDvet, https:// www.id-vet.com),which has a sensitivity of 98.9% (95% CI 96.8%-99.8%)and a specifi city of 100% (95% CI 99.8%-100%) (12).Because CCHFV might have been introduced in the region via ticks carried by migratory birds (3), we selected 226 samples from areas close to the 3 main Hotspot of Crimean-Congo Hemorrhagic Fever Virus Seropositivity in Wildlife, Northeastern Spain