Host diversity and landscape structure drive genospecies-specific Lyme disease risk across Eurasia.

Lyme disease poses an escalating global health challenge partly driven by climate change and land-use transformation, while mechanistic understanding of transmission remains limited. We analyzed prevalence records from 43 Eurasian countries to map pathogen biogeography and applied theory-driven structural equation modeling (SEM) to evaluate hypothesized direct, indirect, and cascading pathways linking climate, land cover, landscape structure, and host biodiversity to pathogen prevalence. Genospecies exhibited distinct biogeographic patterns shaped by vector-host specificity, with Ixodes ricinus dominating transmission in Europe and I. persulcatus in Asia. Borrelia afzelii prevalence was associated with climate, forest fragmentation, and landscape heterogeneity, and exhibited a negative association with rodent species richness at the continental scale. Borrelia garinii showed no host diversity effects but responded directly to temperature and landscape structure, reflecting reliance on highly mobile avian hosts. These findings reveal fundamental transmission heterogeneity among genospecies arising from divergent host-reservoir ecologies, with critical implications for disease control. Effective surveillance must integrate genospecies-specific ecology with landscape management to align biodiversity conservation, climate adaptation, and public health.