The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed last week that the recent detection of highly pathogenic avian influenza (HPAI) in a Wisconsin dairy herd represents a new spillover event from wildlife.
In a December 19 update, APHIS said whole-genome sequencing confirmed that the virus detected in a Wisconsin dairy herd on December 14 is H5N1 clade 2.3.4.4b genotype D1.1, which was implicated in two spillover events in dairy herds in Nevada and Arizona earlier this year. The Wisconsin spillover event is considered separate from those two previous spillovers, APHIS said. No additional infected dairy herds have been detected.
Most H5N1 detections in US dairy cattle have involved the B3.13 genotype, which was initially detected in the Texas Panhandle in late 2023.
“This detection does not pose a risk to consumer health or affect the safety of the commercial milk supply,” APHIS said.
More outbreaks in US poultry
Meanwhile, APHIS is reporting seven new HPAI outbreaks in US commercial and backyard poultry flocks. Two of the outbreaks are in Indiana’s hard-hit LaGrange County, with more than 32,000 birds affected at two commercial facilities. An outbreak at a commercial turkey breeder in Edmunds County, South Dakota, has affected more than 29,000 birds.
Over the past 30 days, 70 US flocks (24 commercial and 46 backyard) have been confirmed as having HPAI, with 820,000 bids affected.