Highly pathogenic avian influenza found in Texas, Kansas dairy cattle

On March 25, the U.S. Department of Agriculture (USDA), Food and Drug Administration (FDA), and Centers for Disease Control and Prevention (CDC) announced the detection of highly pathogenic avian influenza (HPAI) in laboratory samples obtained from some affected cows in Texas and Kansas. Samples netting positive results included unpasteurized, clinical samples of milk from sick cattle collected from two dairy farms in Kansas and one in Texas, as well as an oropharyngeal swab from another dairy in Texas.

These findings mark the first time that HPAI has been detected in dairy cattle, and the second time the virus had been detected in a ruminant. On March 20, the Minnesota Board of Animal Health announced that the virus had been detected in samples from juvenile goats on a Minnesota farm where poultry had recently contracted the virus.

“The detection of HPAI, first in goats and now in dairy cattle, underscores the importance of adherence to biosecurity measures, vigilance in monitoring for disease, and immediately involving your veterinarian when something seems ‘off,’” said AVMA President Rena Carlson. “A complete evaluation, including the collection and submission of laboratory samples and reporting to state animal health officials in a timely fashion, when appropriate, are incredibly important."

This detection of HPAI is tied to the investigation of an illness that has affected dairy cattle on farms in Texas, Kansas, and New Mexico. Sick cows are primarily older animals showing decreased lactation and low appetite, among other clinical signs. On average, about 10% of the herd on these premises appears to be affected, with little to no associated mortality reported. In addition, the dairy farms where HPAI was identified have reported finding deceased wild birds on their properties.

Based on findings from Texas, the virus appears to have been introduced by wild birds. Initial testing by the USDA’s National Veterinary Services Laboratories (NVSL) has not found changes to the virus that would make it more transmissible to humans, which would indicate that the current risk to the public remains low.

Federal and state agencies are moving quickly to conduct additional testing for HPAI, as well as viral genome sequencing, to gain a better understanding of the situation, including characterization of the HPAI strains associated with these detections.

At this stage, the USDA, FDA, and CDC have indicated that they have no concern about the safety of the commercial milk supply or that this circumstance poses a risk to consumer health. Dairies are required to send only milk from healthy animals into processing for human consumption; milk from impacted animals is being diverted or destroyed so that it does not enter the food supply. In addition, pasteurization has continually proven to inactivate bacteria and viruses, such as influenza, in milk. Pasteurization is required for any milk entering interstate commerce.

Federal agencies, working with veterinarians, state animal health officials, and industry partners continue to encourage farmers and veterinarians to report any signs of illness quickly so as to minimize impacts on the cattle, farmers, consumers, and other animals.

This is a rapidly evolving situation and the AVMA, in partnership with the American Association of Bovine Practitioners, and state and federal partners, will continue to share updates as soon as more information becomes available.

For more information about HPAI, visit the AVMA website.