Bird Flu Expands Across Species, Raising Concerns About Surveillance and Mutation Risks

Experts warn of undetected infections in humans and animals as bird flu spreads through birds, mammals, and dairy cattle in the U.S.

The H5N1 avian flu virus has spread widely among birds, mammals, and dairy cattle, with over 68 confirmed human cases in the U.S. since 2024, including one fatality.
A CDC study found antibodies in three veterinarians who were asymptomatic, suggesting silent infections and gaps in surveillance systems.
Two strains of the virus, B3.13 and the newly detected D1.1, have been recorded in dairy cattle, with D1.1 linked to more severe human cases, including one death in Louisiana.
Public health officials emphasize the need for expanded testing and surveillance to track infections in animals and humans and prevent potential mutations or reassortments.
Precautionary measures such as avoiding raw animal products, using protective equipment for farm workers, and monitoring pets are being recommended to reduce the risk of transmission.