Weld County
Bird flu confirmed at Weld County dairy, first Colorado dairy case since August 2024
The dairy is under quarantine, restricting movement of lactating cattle. Weekly bulk milk testing must continue until two consecutive results, at least a week apart, are negative; Colorado says the risk to the public remains low.
The U.S. Department of Agriculture's National Veterinary Services Laboratory confirmed highly pathogenic avian influenza (the B3.13 strain) at a Weld County dairy on Saturday, Oct. 24, the first detection in a Colorado dairy since August 2024.
The dairy has been placed under a quarantine order. The quarantine restricts the movement of lactating dairy cattle from the affected facility, and the operation must immediately implement strict biosecurity protocols across all farm activities and daily routines.
The operation must also undergo weekly bulk milk tank testing until it has two consecutive negative test results at least one week apart. The Colorado State Veterinarian's Office was notified that a sample from a routine bulk milk tank test had tested presumptive positive for the virus.
The risk to the general public remains low and pasteurized milk continues to be safe because pasteurization kills viruses, Colorado said. People most at risk for avian flu are those who come into direct contact with infected birds or other animals.
The Colorado Department of Agriculture is working with the Colorado Department of Public Health and Environment and local partners to protect the health of farmworkers and facility staff.
"This detection underscores the importance of our routine bulk milk tank testing to keep our herds healthy and our food supply secure," said Colorado State Veterinarian Dr. Maggie Baldwin.
Colorado first confirmed a positive detection of the virus in dairy cattle on April 25, 2024, during an outbreak that grew to affect 64 individual dairies across the state. In response, Colorado became the first state in the nation to institute mandatory bulk milk tank testing for all commercial dairies.
All dairies were released from quarantine by December 2024.