Host Community Traits Driving Crimean-Congo Hemorrhagic Fever Virus Maintenance in Iberian Ecosystems.

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne zoonosis of significant public health concern, maintained in complex multihost systems shaped by ecological, climatic, and anthropogenic drivers. In the Iberian Peninsula, changing land-use patterns and biodiversity loss may be reshaping host communities in ways that alter local transmission dynamics. We conducted a landscape-scale study across 18 sites, integrating serological surveillance of wild ungulates (n = 1461; 69.4% wild boar, 30.6% red deer) with camera-trap monitoring of mammalian communities, land cover analysis, and climatic data. To capture ecological drivers at different scales, we fitted two generalized linear mixed models (GLMMs): one including all sites to identify broad landscape-level predictors of exposure, and another restricted to endemic sites to evaluate fine-scale dynamics within established transmission foci. Overall, 44.5% of sampled individuals tested positive for CCHF virus (CCHFV) antibodies, with site-level seroprevalence ranging from 1.5% to 81.4%. Across all sites, seroprevalence was positively associated with red deer abundance, underscoring the potential role of red deer as key amplifying host, forest cover, and precipitation seasonality, while small ruminant presence was linked to reduced exposure risk. Within endemic areas, higher mammalian diversity and greater lagomorph abundance were negatively associated with exposure, whereas warmer temperatures promoted circulation. This pattern suggests that more balanced host communities can reduce the efficiency of pathogen transmission. Overall, this study highlights how community structure and environmental change jointly shape CCHFV ecology. The context-dependent nature of ecological drivers support integrated One Health strategies that conserve biodiversity, promote mixed grazing systems, and regulate wild ungulate populations to reduce CCHFV circulation in Mediterranean ecosystems undergoing socioecological transformation.