Colorado workers are first since 2022 to catch bird flu from poultry

A total of five workers — two more than initially reported — contracted mild cases of bird flu while culling infected chickens with the viral disease on an egg farm, said Colorado public health officials. They were the first poultry workers known to have contracted bird flu since May 2022; four dairy farmworkers have been diagnosed with the disease, which is also spread by cows, since April, including one in Colorado.

The risk to the general public remains low, said the Centers for Disease Control. “These cases again underscore the risk of exposure to infected animals.” The agency said there were no other increases in flu activity in Colorado or in other states with bird flu outbreaks.

“The workers were culling poultry at a farm in northeast Colorado and exhibited mild symptoms, including conjunctivitis (pink eye) and common respiratory infection symptoms. None were hospitalized,” said the state Department of Public Health and Environment. The CDC said besides conjunctivitis and “eye tearing,” the workers reported “more typical flu symptoms of fever, chills, coughing and sore throat/runny nose.”

A nine-member, bilingual CDC field team, including epidemiologists, veterinarians, clinicians, and an industrial hygienist, was deployed to Colorado to assist the state in its investigation. “There is ongoing monitoring of workers as part of this assessment and additional specimens are being tested,” said the CDC.

Earlier this month, the CDC said at least 1,390 people have been monitored since March because of exposure to infected cattle and at least 62 people who developed flu-like symptoms were tested for bird flu. To date, four cases were confirmed; two in Michigan and one each in Texas and Colorado.

The first person in the United States infected by the H5N1 avian flu virus, in May 2022, was a Colorado correctional inmate who, as part of a pre-release program, culled infected poultry at an egg farm in western Colorado.

Bird flu was confirmed in two dairy herds late last week in Oklahoma, making it the 13th state with infected cows. Overall, 157 herds have tested positive for the virus since late March, when bird flu was identified as the mysterious disease circulating among dairy herds in the Texas panhandle. Scientists say the disease jumped to cattle in late 2023 or early 2024 in the panhandle.

Colorado has the largest number of infected herds, 36, followed by Idaho with 30 and Michigan with 26.

The H5N1 avian flu virus has killed more than 99 million birds, mostly egg-laying hens and turkeys being raised for meat, in domestic flocks since it appeared in the United States in February 2022. The 2014-15 outbreak of bird flu killed 50 million birds in domestic flocks and was described at the time as the largest animal disease event in U.S. history.