H5N1 Bird Flu Spreads to New U.S. Dairy Herds, Raising Concerns for Livestock Movement and Biosecurity
Highly pathogenic avian influenza (H5N1) continues to spread among U.S. dairy cattle, with new detections reported in Washington and Indiana. According to the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS), H5N1 has now affected dairy cattle in 21 states since its initial identification in March 2024. The recent cases include two Washington dairy herds in October and an Indiana dairy herd on November 2, which was identified through routine screening via the National Milk Testing Strategy. Federal analyses indicate that much of the spread among dairy herds is linked to livestock movements, with genetic evidence suggesting transmission from Idaho to Washington. Veterinarians and producers are urged to enhance biosecurity protocols, including careful management of incoming cattle, isolation of sick animals, and sanitation of shared equipment, to curb further transmission.