U.S. veterinary authorities monitor several cases of avian influenza found in dairy cows

Multiple highly pathogenic avian influenza outbreaks are being investigated by the U.S. Department of Agriculture (USDA), Food and Drug Administration (FDA), and Centers for Disease Control and Prevention (CDC), as well as state public health and veterinary officials. (HPAI) primarily affects older dairy cows in Texas, Kansas, and New Mexico.

As of yesterday, Monday, March 25, cases have been confirmed in clinical samples of unpasteurized milk from sick cows collected from two dairy farms in Kansas and one dairy farm in Texas. Additionally, traces of the virus were found in oropharyngeal swabs from another Texas dairy farm. Additional testing has been carried out since Friday 22 March and over the weekend as farms also reported dead wild birds found on their land.

Based on findings in Texas, the detections appear to have been introduced by wild birds. Preliminary tests by the National Veterinary Services Laboratory found that the virus has not changed in any way that would make it easier to spread to humans, suggesting that the risk to the population remains low.

Federal and state agencies are moving quickly to conduct additional testing for HPAI and viral genome sequencing to better understand the situation, including the characteristics of HPAI strains associated with these detections.

The veterinary authority said it was not concerned at this stage about the safety of the commercial milk supply or the risk it would pose to consumer health. Regardless, there are calls for dairies to supply only milk from healthy animals for human consumption; milk from affected animals is diverted or destroyed to avoid entering the food supply. Additionally, milk entering interstate commerce is required to be pasteurized.

Federal agencies are also working with state and industry partners to encourage ranchers and veterinarians to promptly report livestock diseases so they can monitor potential additional cases and minimize impacts to ranchers, consumers and other animals. For dairy farms with symptomatic herds, on average approximately ten percent of each affected herd appears to be affected, but few animal-related deaths have been reported. To date, milk losses from symptomatic cows have been too limited to have a significant impact on supply or the price of milk or other dairy products.