Avian flu detected in another Colorado dairy

Avian flu has been detected at a Weld County dairy, the first time in more than two years that a case of the flu spread by birds has been found at a commercial farm in Colorado. 

The risk of humans getting infected by drinking milk is low. When milk is pasteurized, the process would kill the virus, state health officials said Friday. 

The U.S. The Department of Agriculture confirmed the case of “highly pathogenic avian influenza” at a Weld County dairy, the first since August 2024. Colorado began routine bulk milk tank testing to check for the bird flu in the milk supply after avian flu was first detected at dairy farms in the state in April 2024 in an outbreak that grew to 64 dairies. 

The testing performed at Colorado State University’s veterinary lab detected the avian flu, and the finding was confirmed by the National Veterinary Services Laboratory on Oct. 24. The dairy, which was not identified by state officials, has been put under quarantine, which means that milk cows cannot leave the dairy and that the dairy must enact strict biosecurity protocols. Weekly bulk milk tank testing will continue until the dairy tests negative for two weeks in a row, state officials said. 

“This detection underscores the importance of our routine bulk milk tank testing to keep our herds healthy and our food supply secure,” state veterinarian Dr. Maggie Baldwin said in a news release. “Colorado has taken a proactive approach to monitoring and responding to avian influenza, ensuring that early detection leads to swift mitigation measures to protect consumers and our food supply.”

People are most at risk of contracting avian flu by coming in contact with infected birds or animals, not by drinking milk, especially pasteurized milk, state health officials said. 

In January, Colorado found avian flu in a commercial chicken farm, also in Weld County. In past years, under state orders, Colorado commercial egg farms had to kill millions of chickens to head off avian flu outbreaks spreading to other farms and wild bird populations. The crossover to dairy farms came in 2024. 

Colorado became the first state in the nation that year to institute mandatory bulk milk tank testing for commercial dairies. The effort had cleared all affected herds, with all dairies released from quarantine by December 2024.