November 4, 2026 - On October 8, 2026, USDA´s Animal and Plant Health Inspection Service (APHIS) announced the first two detections of highly pathogenic avian influenza (HPAI) in two dairy herds in Washington. On October 8, the National Veterinary Services Laboratories (NVSL) completed whole genome sequencing and confirmed that the virus is H5N1 genotype B3.13. Analysis indicates that this detection is consistent with transmission of virus from Idaho to Washington likely through cattle movement.
Key Points
Most cases in U.S. dairy herds have resulted from live animal movements linked to the original spillover event that was detected in the Texas Panhandle in late 2023, involving the B3.13 genotype.
The Washington herds, detected after exhibiting clinical signs consistent with H5N1, is due to the B3.13 strain. At this time, surveillance is ongoing around the initial premises and throughout Washington.