A spatial, agent-based model to explore mechanisms of bluetongue virus persistence at the interface of domestic and wildlife ruminant populations

Bluetongue virus (BTV) is a vector-borne pathogen that affects both domestic and wild ruminants, posing significant concerns for livestock production and wildlife health. While the role of wildlife hosts in BTV dynamics has been hypothesized, especially in regions with large domestic–wildlife interfaces, their species-specific contributions remain poorly understood. We developed a spatially explicit, agent-based simulation model to assess how different wildlife species may facilitate BTV transmission under varying ecological and epizootiological assumptions. The model simulates BTV spread across two counties in Northern Colorado, incorporating mobile wildlife herds, domestic animals with associated midge populations, and standalone midge habitats. After calibration to locally collected data, we explored three scenarios reflecting different assumptions about wildlife species and conducted a series of parameter perturbations alongside leave-one-out (LOO) style host exclusion experiments. A key finding is that the dominant contributor to BTV transmission alternates between mule deer and white-tailed deer, depending on assumptions about enzootic circulation in each species and species movement patterns. This species-level dominance is generally robust to parameter variation, though shifts emerge under altered wildlife travel volatility. In particular, increased volatility in mule deer or white-tailed deer movement amplifies their role in our model of BTV spread and modifies the relative importance of other species. Our findings underscore the importance of spatial distribution and host mobility in shaping transmission dynamics in multi-host systems. This simulation framework provides a foundation for future efforts to evaluate targeted surveillance or control strategies that account for species-specific and spatial factors and could serve as a foundation for exploring additional aspects of herd dynamics in BTV ecology.