Spatial correlation of feline H5N1 spillover with wild bird and agricultural sources of avian influenza in the US, 2021-2024

Current H5N1 (2.3.4.4b) Highly Pathogenic Avian Influenza has been devastating to poultry industries and wild bird populations in the US since 2021, with concerning mammalian spillover and cattle transmission. Domestic and wild cats have experienced fatal neurologic disease following H5N1 infection, but their role in domestic-wildlife-human transmission is unknown. We summarized the spatial associations of confirmed US H5N1 felid cases relative to wild and agricultural avian sources to explore their landscape epidemiology. County-level data from 76 feline cases, >73k sampled wild birds for Influenza A surveillance testing, and >100M poultry affected by outbreaks were included from Dec 2021-April 2024. All samples were screened via Influenza A PCR, subtyped and sequenced for confirmation by the National Veterinary Services Laboratory. Pooled county-level prevalence in wild birds compared H5 detections over total tested, with county sums of affected domestic birds. Hot spot analysis in ArcGIS detected statistically significant hot and cold spots of virus burden for wild and domestic avian sources. Felids were summarized by number of cases, species, and known agricultural links. Spatially, 29 (38%) feline cases occurred in counties without known avian detections, with 12 domestic cat clusters associated with agricultural outbreaks. Hot spots of avian sources of virus did not explain patterns of feline infections alone. In contrast, only recently (Spring 2024) have increased agricultural-associated infections been described. While results may in part represent missing data and changing viral dynamics, felids may be useful sentinels in under-surveilled counties. Continued monitoring is required to better understand mammalian spillover and pandemic preparedness.

Treana Mayer1, Jourdan Ringenberg2, Krista Dilione 2, Julianna Lenoch 2, Sue VandeWoude 1 & Sarah Bevins 2 1 Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO; 2 National Wildlife Research Center, Wildlife Services, United States Department of Agriculture, Fort Collins, CO

Avian influenza in mammals, pandemic preparedness, and one health