About avian influenza

Avian influenza is a type A virus known for causing bird flu in humans, pigs, horses, cats and other species as of 2024. Scientists use genotypes, or the genetic sequences of the virus, to track and find effective treatments. For example, the genotype for H5N1 found in cattle is a different H5N1 than that found in pigs. The H5N1 strain has adapted to birds and is circulating in wild waterfowl such as free-ranging dabbling ducks and geese. 

Bird influenza viruses are classified as low pathogenic or high pathogenic based on how the virus affects chickens. In this instance, the virus is highly transmissible and deadly for chickens. However, there is a low consequence in wild waterfowl and free-ranging dabbling ducks and geese; we don't see much disease in those species. The problem is when the virus jumps species and ends up in domestic poultry or potentially other avian species, where we see high consequences.

According to the federal Centers for Disease Control and Prevention, the risk to humans remains low. Isolated cases with infected farm workers started showing up in April 2024. Ohio had its first human case in February 2025. One isolated case of a non-farm worker resulted in death in the U.S. The person had underlying health issues and was exposed to wild birds and a backyard flock of poultry.