Colorado is grappling with an alarming outbreak of avian flu, which has spread to its dairy industry, with ten new cases identified in dairy herds through mandatory milk tank testing. The state’s Agriculture Department, in an effort to curb the spread of the highly pathogenic avian influenza (HPAI) H5N1, has implemented a weekly testing program. This program aims to protect the state’s vital dairy and poultry industries, which are at risk of significant economic losses due to the disease.
The mandatory testing was ordered by the state veterinarian as a proactive measure after bird flu was first detected in cattle in late March. Since then, the disease has been confirmed in 63 dairy herds across Colorado, accounting for nearly one-third of the 190 outbreaks recorded in 13 states, spanning from Idaho to North Carolina. The severity of the situation is underscored by the fact that 11 of the 12 cases reported in August have been in Colorado, with the remaining case detected in Texas.
The spread of bird flu to cattle has been an unexpected development, complicating efforts to control the virus. The USDA’s strategy for eradicating avian flu in cattle involves isolating infected farms and waiting for the virus to die off naturally. Although the virus causes symptoms such as fever, reduced appetite, and decreased milk production, the cattle generally recover within a few weeks, and the mortality rate remains low.
Public health officials have emphasized that the risk to the general public is minimal, as there have been no indications that the virus is evolving to become more transmissible among humans. Additionally, there has been no uptick in flu activity linked to this outbreak. However, 13 farmworkers—four on dairy farms and nine on poultry farms—have contracted mild cases of bird flu since April, with 10 of these cases occurring in Colorado. The affected workers have experienced only mild symptoms, and there has been no evidence of sustained human-to-human transmission.
The discovery of the new infections in Colorado was the first major success of the state’s bulk tank surveillance program. The program, which tests milk samples from bulk tanks on dairy farms, detected these cases during routine weekly checks. This testing program is unique to Colorado, making it the only state with mandatory testing in place to monitor the spread of avian flu within its dairy industry.
In response to the outbreak, the USDA has rolled out several support measures for affected farmers. Dairy farmers are being offered up to $28,000 in financial assistance to enhance biosecurity measures, purchase protective gear for workers, and cover veterinary expenses associated with treating and testing herds for bird flu. Additionally, compensation for lost milk production is available to help mitigate the economic impact on farmers.
To further support the dairy industry, the USDA launched a voluntary dairy herd status program in late May. This program allows dairy farms to transport lactating cows across state lines without the need for bird flu testing, provided their milk samples have tested negative for three consecutive weeks. As of now, 24 herds across 10 states have enrolled in the program, with 10 of these herds located in Michigan.
The ongoing battle against avian flu in Colorado highlights the challenges faced by the dairy industry in controlling the spread of the virus. With nearly 101 million birds in domestic flocks—mostly egg-laying hens and turkeys—having died from bird flu since the virus appeared in the U.S. in February 2022, the stakes are high. Colorado alone has lost 9.7 million birds, underscoring the urgency of containment and prevention efforts. As the situation continues to evolve, the effectiveness of the state’s proactive measures will be closely watched by the agricultural community nationwide.
