USDA confirms bird flu case in Wisconsin dairy herd as new wildlife spillover

The genetic sequencing of the bird flu virus (highly pathogenic avian influenza) detected in a Dodge County dairy herd earlier this month indicates it was likely a new spillover event from wildlife.

Wisconsin agriculture officials reported during a recent media briefing that the National Veterinary Services Laboratories (NVSL) completed whole genome sequencing on Dec. 17 and confirmed that the virus is H5N1 clade 2.3.4.4b genotype D1.1.

Elizabeth Patton, assistant state veterinarian with the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP), said most detections in U.S. dairy herds have resulted from movements linked to the original spillover event that occurred in the Texas Panhandle in late 2023, involving the B3.13 strain.