At least four workers at a Colorado poultry farm have been diagnosed with bird flu, state health officials said Sunday. That brings the total to nine reported cases in the United States since the first of the current outbreak in humans was detected in 2022. Eight of those have been reported this year.
All four workers had mild symptoms such as red and irritated eyes, fever, chills, cough, sore throat and nasal congestion, common with a respiratory infection. None have been hospitalized. The other reported cases were also not serious.
A fifth person with symptoms is being tested, but the results of his or her tests are not yet ready, according to authorities.
The workers were slaughtering birds at a farm in northeastern Colorado and had direct contact with infected animals.
An avian influenza virus (H5N1) has been spreading in different countries since 2020 among mammals, including dogs, cats, bears, skunks and even seals and porpoises. Earlier this year it was detected in livestock in the United States in several states.
Federal health officials consider the threat to the public to be low because the virus has not spread from person to person, but they are maintaining careful surveillance because previous versions of the same virus have been fatal among humans.
At the state’s request, the Centers for Disease Control and Prevention (CDC) has sent a nine-person team to Colorado to assist with the investigation.
The other cases reported earlier this year were among dairy farm workers in Michigan, Texas and Colorado. The virus detected in the latest four cases is partially identical to the type found in the earlier ones, but ongoing genetic analysis will determine in the future whether it is the same, according to authorities.
As of Friday, the H5N1 virus had been confirmed in 152 dairy herds, according to the USDA. Hundreds of commercial poultry farms in more than 30 states have reported H5N1 or other types of bird flu.
