Bird Flu Virus Discovered in U.S. Dairy Cows for the 1st Time

Health officials are worried about the highly pathogenic avian influenza (HPAI) virus, also known as bird flu, spreading after it was found to have infected cows for the first time.

The virus has been known to cause outbreaks in commercial and backyard poultry flocks, and sporadic infections in mammals. However, HPAI in dairy cows was first reported in Texas and Kansas by the U.S. Department of Agriculture (USDA) on March 25. Unpasteurized milk from sick cattle collected from dairy farms in Kansas and Texas tested positive for HPAI A(H5) viruses. As of April 22, eight states have confirmed H5 bird flu in dairy cows. Infection is causing decreased lactation, low appetite, and other symptoms in affected cattle.

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While the USDA, Food and Drug Administration (FDA), Centers for Disease Control and Prevention and public health officials investigate the outbreak impacting dairy cows in multiple states, health officials assure that the commercial milk supply is still safe. This is because nearly all (99%) of the commercial milk supply that is produced on dairy farms in the United States comes from farms that participate in the Grade “A” milk program and follow the Pasteurized Milk Ordinance (PMO), which helps ensure the safety of dairy products. The pasteurization process kills harmful bacteria and viruses by heating milk to a specific temperature for a set period of time. Even if virus is detected in raw milk, pasteurization is generally expected to eliminate pathogens to a level that does not pose a risk to consumer health. 

Additionally, affected dairy cows are being segregated and their milk does not enter the food supply. According to dairy farmers and veterinarians, most affected cows recover within two to three weeks.

During the course of the outbreak, the FDA has been evaluating milk from affected animals, in the processing system, and in grocery stores. 

“To date, we have seen nothing that would change our assessment that the commercial milk supply is safe,” the agency said in its statement.

Bird flu viruses do not normally infect humans. One human case from a person exposed to infected cows linked with this outbreak developed a mild eye infection and has recovered. CDC says risk to the general public remains low. 

Meanwhile, the United States has also been contending with outbreaks of HPAI in the egg market this year, affecting supplies and driving up egg prices.