A man in Colorado is the first person in the U.S. diagnosed with the H5N1 virus, also known as the bird flu or avian flu.
The Colorado Department of Public Health and Environment (CDPHE) says the man, who is younger than 40, has only reported feeling fatigued.
Health officials said the man had been working on a farm with infected poultry.
He is reportedly an inmate at a Colorado correctional facility who had been working as part of a pre-release employment program.
The risk of the virus spreading to other people is low, the CDPHE said.
"There are currently no known cases of this H5 flu virus spreading among people," the agency said in a statement. "There are no other confirmed human cases in Colorado or the United States at this time."
The birds that were believed to be infected or at risk of infection were euthanized, officials said.