Bird flu found in northeastern Colorado dairy herd
Colorado is now one of nine states in which dairy cattle have tested positive for avian influenza.
A U.S. Department of Agriculture laboratory confirmed Thursday the detection of Highly Pathogenic Avian Influenza H5N1 from dairy cows in a northeastern Colorado herd. It is the first detection of the disease in Colorado.
The Colorado State Veterinarian's office was notified Monday about a herd demonstrating clinical symptoms of HPAI in cattle, a Colorado Department of Agriculture press release stated.
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Bird flu was first detected in a Texas dairy herd on March 25.
"We continue to see this ongoing HPAI outbreak evolve and over the last month have seen transmission of the virus now move into dairy cattle. While we don't yet completely understand the mechanism of transmission of this virus, we do know that it appears to be spreading from cow to cow and between herds," stated Colorado State Veterinarian Dr. Maggie Baldwin. "It is critically important that producers implement enhanced biosecurity measures to mitigate the spread of highly pathogenic avian influenza."
Infected cattle typically exhibit a decrease in appetite and milk production. The milk also appears abnormally "colostrum-like," per the USDA.
However, cattle usually recover with sufficient care.
The USDA and U.S. Food and Drug Administration have both declared commercially produced milk to be safe for consumers.
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"Pasteurization has continuously proven to inactivate bacteria and viruses in milk," the CDA's press release stated. "The risk to the general public remains low, per (the Centers for Disease Control and Prevention). H5N1 remains mainly an agricultural issue in poultry and now in dairy cows. Two human cases of H5N1 have been reported in the United States, one in Colorado in 2022 and one in Texas in 2024. Both cases had minimal symptoms following exposure to infected animals. No person-to-person spread has been identified associated with the current H5N1 virus."
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Colorado has 106 dairies and approximately 200,000 dairy cows.
The USDA issued a federal order Wednesday requesting dairy farms limit the transport of their animals. The transportation of lactating cows over state lines must adhere to specific USDA guidelines, including pre-testing.
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The Colorado State Fair begins Aug. 23 and features pig, sheep, goats, poultry, beef cattle and dairy cattle shows. Several county fairs with similar exhibitions begin in July during the lead up to the state contest. State officials have not yet released information about bird flu's impact to these events.