Colorado’s required milk tank testing has caught a bird flu infection at a Weld County dairy, the state’s first dairy case since 2024. The Colorado Department of Agriculture said Oct. 30, 2026, that routine bulk milk tank sampling produced a presumptive positive at Colorado State University’s diagnostic lab. USDA’s national lab confirmed highly pathogenic avian influenza on Oct. 24, and the genotype is B3.13.
The B3.13 genotype is the strain that has circulated in U.S. dairy cattle since the 2024 outbreaks, including Colorado’s. The dairy is under quarantine, with movement of lactating cattle restricted and strict biosecurity required. It must test its bulk tank weekly until it posts two consecutive negative results at least one week apart.
For shoppers along the Front Range and beyond, the state’s message is direct: “The risk to the general public remains low, and pasteurized milk continues to be safe, because pasteurization kills viruses.” The policy question is what the detection says about milk surveillance as states test less often.
Detection Through the Tank, Not the Barn
Colorado made bulk milk testing mandatory for commercial dairies during its 2024 outbreak, which affected 64 dairies. The state says it was the first in the nation to require it. Every dairy was released from quarantine by December 2024…