Routine milk testing identifies a new case of highly pathogenic avian influenza as state officials emphasize that pasteurized milk remains safe.
By North Forty News Staff | NorthFortyNews.com
A Weld County dairy has tested positive for highly pathogenic avian influenza (HPAI), marking Colorado’s first confirmed detection of the virus in dairy cattle since August 2024.
The Colorado Department of Agriculture announced that the U.S. Department of Agriculture’s National Veterinary Services Laboratories confirmed the HPAI B3.13 strain on October 24, after a presumptive positive result from routine bulk milk tank testing.
State agriculture and public health officials placed the affected dairy under quarantine as they work to prevent further transmission.
“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 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.”
Quarantine and Testing Requirements
The quarantine restricts movement of lactating dairy cattle from the affected facility and requires enhanced biosecurity measures throughout the operation.
The dairy must also undergo weekly bulk milk tank testing until it records two consecutive negative results at least one week apart.
The Colorado State University Veterinary Diagnostic Laboratory identified the initial positive sample as part of Colorado’s ongoing surveillance program.
State officials have not identified the affected dairy in the announcement.
Public Health Risk Remains Low
The Colorado Department of Agriculture is coordinating with the Colorado Department of Public Health and Environment and local partners to monitor potential exposures among farmworkers and other personnel.
People who work directly with infected animals or contaminated raw animal products face the greatest risk of exposure.
According to state officials, the risk to the general public remains low. Commercially pasteurized milk remains safe to consume because the pasteurization process inactivates influenza viruses.
Public health officials routinely monitor people who may have been exposed to infected animals as a precaution.
Colorado’s Previous Dairy Outbreak
Colorado confirmed its first HPAI infection in dairy cattle on April 25, 2024. The outbreak eventually affected 64 dairy operations statewide.
In response, Colorado became the first state to require routine bulk milk tank testing at all commercial dairies, creating a surveillance system designed to identify infections before they spread more widely.
By December 2024, all affected Colorado dairies had been released from quarantine.
The latest Weld County detection represents the first confirmed return of the virus to a Colorado dairy herd in more than two years.
The state’s surveillance program remains in place, allowing agricultural officials to identify new infections and implement containment measures.
For Northern Colorado, where dairy farming is an important part of the agricultural economy, the detection highlights the continuing importance of disease monitoring and biosecurity protections.
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