Trends associated with avian influenza spillover into United States poultry farms: environmental correlates, regional dynamics, and potential biosecurity protections

Transfer of HPAI between wild birds and poultry farms drives disease dynamics, as viruses circulating in both systems propagate, mutate, and reassort. Dynamics of the wild disease system are broadly driven by climate and migratory movements of wild birds, and locally by their habitat preferences once settled. Given this, observations of when and where spillover events occur are indicators of the spatiotemporal dynamics of exposure to HPAIV on the landscape for both wild and domestic populations. By accounting for such dynamics, we can also assess the impacts of biosecurity measures implemented at poultry farms while simultaneously accounting for their local risk levels. To achieve this, we implemented a joint-likelihood logistic regression model, where we compared models of spatiotemporal risk according to land use, weather, predicted waterfowl distributions. We then integrated a case-control questionnaire dataset, which surveyed farms with known outbreaks and paired control locations, to identify trends in HPAI spillover risk associated with a farm’s biosecurity practices. We found that estimates of waterfowl abundance, along with mean precipitation and temperature during winter, best described spatiotemporal HPAI risk. We additionally identified multiple biosecurity practices associated with reduced risk to HPAI, where the strongest relationships were related to litter decontamination treatments, vehicle wash stations, and shared dead-bird disposal sites with other farms. This model broadly guides surveillance of AIV in wild populations, identifying when and where we are most likely to see increased instances of the virus while also providing insights into how poultry farms can better protect themselves from risk.

Matthew Gonnerman (1,2), Andrew Fox (3), Kelly A. Patyk (3), Mary-Jane McCool (3), Mia K. Torchetti (4), Jeffery D. Sullivan (5), Jennifer M. Mullinax (1), Diann J. Prosser (5) 1) Department of Environmental Science and Technology, University of Maryland, College Park, MD 20742, USA 2) Post-doctoral affiliate with the U.S. Geological Survey, Eastern Ecological Science Center, Laurel, MD 20708, USA 3) United States Department of Agriculture, Animal Plant and Health Inspection Service, Veterinary Services, Strategy and Policy, Center for Epidemiology and Animal Health 4) National Veterinary Services Laboratories, Animal and Plant Health Inspection Service, USDA, Ames, IA, 50010, USA 5) U.S. Geological Survey, Eastern Ecological Science Center, Laurel, MD 20708, USA

Notable outbreaks, field and molecular epidemiology, and surveillance in wild birds