Update: Genetic Sequencing Results for Washington Dairy Herd Detection of Highly Pathogenic Avian Influenza

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WASHINGTON, D.C., October 13, 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.

Public Health and Food Safety

This detection does not pose a risk to consumer health or affect the safety of the commercial milk supply. Pasteurization effectively inactivates HPAI virus, and milk from affected animals is diverted or destroyed to prevent entry into the food supply. The Centers for Disease Control and Prevention (CDC) continues to consider the risk to the public to be low.

The Importance of Biosecurity

USDA remains committed to working with state partners to monitor, investigate, and mitigate the spread of HPAI in livestock. The detection does not change USDA's HPAI eradication strategy. Biosecurity is still key to mitigating the risk of disease introduction or spread between premises.

APHIS recommends enhanced biosecurity measures for all dairy farms. Producers should immediately report any livestock with clinical signs, or any unusual sick or dead wildlife, to their state veterinarian.