Routine Milk Tank Testing Detects Colorado's First Dairy HPAI Case Since 2024

The risk to the general public is low and pasteurized milk continues to be safe because pasteurization kills viruses

The U.S. Department of Agriculture's National Veterinary Services Laboratory (NVSL) has confirmed a detection of Highly Pathogenic Avian Influenza (HPAI) in a dairy in Weld County. This is the first HPAI detection in a Colorado dairy since August 2024. Since the initial detection of HPAI in dairy cattle in April 2024, Colorado has implemented routine bulk milk tank surveillance testing to ensure Colorado's milk supply is not impacted.

"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."

The Colorado State Veterinarian's Office was notified by the Colorado State University Veterinary Diagnostic Laboratory that a sample from a routine bulk milk tank test tested presumptive positive for HPAI. The National Veterinary Services Laboratory (NVSL) issued the official confirmation of the detection of HPAI (B3.13 strain) in a dairy in Weld county on Saturday, October 24. The dairy has been put under a quarantine order.

Under the quarantine order, several mandatory stipulations are in effect to prevent further transmission of the virus. The quarantine restricts the movement of lactating dairy cattle from the affected facility. In addition, the operation must immediately implement strict biosecurity protocols across all farm activities and daily routines. To monitor and verify disease status, weekly bulk milk tank testing is required until two consecutive negative test results are obtained at least one week apart.

CDA is working closely with the Colorado Department of Public Health and Environment and local partners to protect the health of farmworkers and facility staff. Public health officials routinely monitor individuals following potential exposure to infected animals or raw animal products as a standard precaution. People most at risk for avian flu are those who come directly into contact with infected birds or other animals. The risk to the general public remains low and pasteurized milk continues to be safe, because pasteurization kills viruses.

Colorado originally confirmed its first positive detection of HPAI in dairy cattle on April 25, 2024, during an outbreak that grew to affect 64 individual dairies across the state. In response to the widespread outbreak, Colorado became the first state in the nation to institute mandatory bulk milk tank testing for all commercial dairies in Colorado. That comprehensive monitoring effort successfully cleared all affected herds, with all dairies released from quarantine by December 2024.