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Highly Pathogenic Avian Influenza in US Dairy Cattle

April 2, 2024

Highly Pathogenic Avian Influenza in US Dairy Cattle

4.2.24 Update:

On 3/28, the Idaho State Department of Agriculture (ISDA) issued a press release with an announcement about the detection of Highly Pathogenic Avian Influenza (HPAI) in a Cassia County, Idaho dairy. ISDA reported that the affected dairy had recently imported cattle from another state that has identified cases of HPAI in cattle, which suggests that the virus may be transmitted from cow-to-cow, in addition to previous reports indicating cattle were acquiring the virus from infected birds.

On 3/29, the USDA issued an updated press release, announcing the confirmation of HPAI in a Michigan dairy farm, as well as the presumptive diagnosis of HPAI in at least one dairy farm in New Mexico. USDA confirmed that the Michigan case is very similar to the strain confirmed in Texas and Kansas that appears to have been introduced from wild birds in those states. Initial testing has not found changes to the virus that would make it more transmissible to humans. While cases among humans in direct contact with infected animals are possible, this current finding indicates that the current risk to the public remains low.

Similarly to the Idaho herd, spread of symptoms among the Michigan herd also indicates that HPAI transmission between cattle cannot be ruled out.

There continues to be no concern about the safety of the commercial milk supply because commercial milk products are pasteurized before entering commerce.

ODA is continuing to work with neighboring states and USDA to monitor this evolving situation and is advising veterinarians and producers to practice good biosecurity, test animals before necessary movements, minimize animal movements, and isolate sick animals from the herd. Among the dairies whose herds are exhibiting symptoms, the affected animals have recovered after isolation with little to no associated mortality reported.

Source: ODA

In late March, the United States Department of Agriculture (USDA) announced the detection of Highly Pathogenic Avian Influenza (HPAI) in milk and nasal swabs collected from dairy cattle in Texas and Kansas. All four dairies had cows that were exhibiting symptoms consistent with a syndrome that has been affecting dairy cattle in the Texas panhandle, New Mexico, and Kansas since early February.

At this stage, there is 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, like influenza, in milk.

While no cases have been reported in Oregon, the Oregon Department of Agriculture (ODA) is working closely with partners from the Oregon Department of Fish and Wildlife (ODFW), Oregon Health Authority (OHA), and USDA, as well as Oregon livestock industry leaders to provide information to Oregon livestock producers, and develop plans to respond if a suspected case is reported in Oregon.

The USDA reports that for the dairies whose herds exhibit symptoms, on average, about ten percent of each affected herd appears to be impacted, with little to no associated mortality reported among the animals. Reported symptoms include:

  • Decreased herd-level milk production
  • Sudden drop in production
  • Decrease in feed consumption
  • Abnormal feces and fever in some cows

ODA is encouraging livestock producers to work closely with their herd veterinarians to ensure that appropriate biosecurity measures are employed on farms to prevent the introduction of diseases. The National Dairy FARM Program and the Beef Quality Assurance program provide additional biosecurity resources for cattle producers.

Source: ODA

Updated: April 2, 2024