Utilizing serology to better understand trajectory and impacts of highly pathogenic avian influenza in wildlife

Since introduction into North America in 2021, highly pathogenic (HP) H5N1 avian influenza A (IAV) has spread rapidly in wildlife, with infection confirmed in over 200 avian species, and mammals, across North and South America; it also continues to impact domestic animal health. An expanding list of impacted species highlights the need to better understand the potential seasonal, spatial, and species-related risks of HP H5N1 in wildlife. Actual rates of exposure and associated impacts are hard to estimate from observational and virologic data alone. In collaboration with state, federal, and academic partners, we have been testing pro- and retrospectively collected serum from a wide-range of wildlife species. Sera are screened by IAV bELISA, and then subsequently tested by virus neutralization and hemagglutination inhibition to detect antibodies to H5 (2.3.4.4b and North American origin low pathogenicity (LP)), and N1 enzyme-linked lectin assay. Thus far, in waterfowl, the observed patterns as related to prevalence of HP H5N1 and resultant immunologic responses, are similar to the seasonal dynamics of LP IAV which are driven by population immunity. In other species for which LP IAV trends have not been well-defined (ex. bald eagles, black vultures, mammals), serologic evidence supports potential resiliency in some populations after initial exposure to HP H5N1. Continued virologic monitoring of wildlife species, inclusive of both LP and HP IAV, is key to helping define viral prevalence and diversity; however, the context that serologic monitoring provides is critical to understanding the potential trajectory of HP H5N1 across North America.

Rebecca Poulson1, Deborah L. Carter1, Zijing Cao1, Morgan Grey1, Paige Palomaki2, Victoria Hall2, Jacqueline Nolting3, David E. Stallknecht1 1 Southeastern Cooperative Wildlife Disease Study, University of Georgia, Athens, GA 2 The Raptor Center, University of Minnesota, Minneapolis, MN 3 The Ohio State University, Department of Veterinary Preventative Medicine, Columbus, OH

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