Four poultry workers in Colorado have been diagnosed with bird flu, health officials confirmed on Sunday.
This brings the U.S. total to nine cases since the first human case of the current outbreak was detected in 2022, also involving a Colorado poultry worker. Eight of these nine cases have been reported this year.
The affected individuals experienced mild symptoms, such as reddened and irritated eyes, fever, chills, coughing, sore throat, and runny nose. None required hospitalization. Previous U.S. cases have also shown mild symptoms.
A fifth person is currently undergoing testing for bird flu, but results are pending. The workers were culling poultry at a farm in northeast Colorado and had direct contact with infected birds.
Since 2020, the bird flu virus, known as H5N1, has spread among mammals, including dogs, cats, skunks, bears, seals, and porpoises, in numerous countries. Earlier this year, H5N1 was detected in U.S. livestock and is now circulating in cattle in several states.
Health officials state that the threat to the general public remains low, as the virus has not spread between people. However, they continue to monitor the situation closely because previous versions of the virus have been deadly to humans.
The Centers for Disease Control and Prevention (CDC) has sent a nine-person team to Colorado to assist with the investigation at the state’s request.
Earlier this year, similar cases were reported among dairy farm workers in Michigan, Texas, and Colorado.
The virus detected in the four latest cases is at least partly identical to the type found in earlier U.S. cases, but further genetic analysis is underway to confirm this, officials said.
As of Friday, the H5N1 virus has been confirmed in 152 dairy herds across 12 states, according to the U.S. Department of Agriculture. Additionally, hundreds of commercial poultry flocks in more than 30 states have reported H5N1 or other types of bird flu.
