A Geospatial Analysis of HPAI Spillover Risk Between Wild Avian Hosts and Commercial Poultry in the United States

Abstract

Highly Pathogenic Avian Influenza (HPAI) is an emerging zoonotic disease of global concern, driven by transmission between wild avian hosts and commercial poultry. Understanding where these populations overlap is critical for predicting and mitigating spillover risk. This study aimed to identify geographic hotspots of potential HPAI spillover across the contiguous United States using a geospatial analysis. Relative abundance data for 157 wild avian host species were integrated with county-level poultry density data to construct a multiplicative spatial Risk Index. To identify extreme spillover interfaces, county-level risk values were standardized using Z-score normalization, with thresholds of Z > 3 and Z > 4 used to define high and extreme-risk counties, respectively. Spatial statistical analyses, including Spearman’s rank correlation and Global Moran’s I, were conducted to assess relationships and clustering patterns. All data analysis and associated code can be accessed through the GitHub repository (Appendix A). In addition, a field study in South Texas collected 111 avian fecal samples to test for the presence of HPAI and Avian Bornavirus (ABV) in urban bird communities (Appendix B). Results revealed no significant global correlation between poultry and wild host densities (ρ ≈ 0, p = 0.953), but a strong, significant spatial clustering of high-risk interfaces (Moran’s I = 0.610, p < 0.001). The Z-score analysis identified 53 high-risk counties (Z > 3) and 28 extreme-risk counties (Z > 4), representing less than 1% of U.S. counties. These high-risk areas were concentrated in major agricultural and migratory regions, including the Mississippi River Basin, Mid-Atlantic, Southeast, and California Central Valley. All field samples tested negative for both pathogens. These findings demonstrate that HPAI spillover risk is highly localized rather than uniformly distributed, highlighting the importance of targeted, spatially informed biosecurity strategies.