#18,620
Nine days ago the USDA confirmed an outbreak of a new genotype (D1.1) of H5N1 in dairy cattle in Churchill County, in Northwest Nevada. This was the first time any genotype other than B3.13 had been detected in cattle in the United States.
Four days ago, Nevada confirmed their first human infection with this genotype, which is circulating in wild birds and has infected scores of poultry farms across the nation over the past few months.
Today, somewhere between 500 and 600 miles to the south and east of the Nevada outbreak, Maricopa County, AZ announced the detection (via bulk milk testing) of H5N1 genotype D1.1 in a dairy herd. According to this press release, this outbreak is unrelated to the Nevada outbreak, which suggests another spillover event.
While details are scant at this time, we have the following press release from Maricopa County.
Avian influenza found in dairy cattle in Maricopa County
On February 11, 2025 the Arizona Department of Agriculture (AZDA), working in conjunction with the United States Department of Agriculture (USDA), confirmed Arizona’s first identified H5N1 avian influenza detection in milk produced by a dairy herd in Maricopa County. As a protective measure, the facility is currently under quarantine. Unlike other detections involving B3.13 H5N1, cattle have not yet displayed signs of illness with this particular D1.1, but if clinical symptoms become evident, cattle will be isolated from the main herd.
This detection stemmed from AZDA’s implementation of the National Milk Testing Strategy initiated in January focusing on farm-level bulk tank testing. This detection of avian influenza is consistent with a D1.1 genotype and unrelated to the recent Nevada detection of this virus. This D1.1 genotype bears no features that would make it more likely to infect humans. Every dairy in Arizona has been tested at least once since January; thus far only a sample from this dairy has tested positive. Milk and other dairy products that have been pasteurized are safe to consume.
The health and safety of dairy workers and the public are AZDA's top priority. AZDA is working closely with the Arizona Department of Health Services and the Maricopa County Department of Public Health to provide worker safety guidance, monitor staff at the affected site, and prevent spread among livestock. Overall, the risk to the general public remains low. Individuals in close contact with dairy cattle may be at increased risk due to contact with potentially affected animals.
Source
Arizona Department of Agriculture
February 14, 2025 - 12:15pm
