CDC Sends Team to Colorado Over Bird Flu After Governor Declares Disaster

There is currently a ‘low’ risk to the public, the agency said, adding that ’there are no signs of unexpected increases in flu activity otherwise in Colorado.'

The Centers for Disease Control and Prevention headquarters in Atlanta on April 23, 2020. (Tami Chappell/AFP via Getty Images

The U.S. Centers for Disease Control and Prevention (CDC) is sending a team to Colorado after the state reported that three people tested positive for bird flu.

The move comes days after the governor declared a disaster over the virus in a northeast county.

Three people tested “presumptive positive” for the highly pathogenic avian influenza H5N1, the CDC said, citing the Colorado Department of Health. The CDC said that specimens were sent to the agency for confirmation.

“All of the people who tested presumptive positive experienced mild symptoms and were workers who were involved in the depopulation of poultry at a poultry facility experiencing an outbreak of the H5N1 virus that is circulating in wild birds and has been causing multistate outbreaks in dairy cows and poultry,” the agency said on July 12.

On July 5, Gov. Jared Polis, a Democrat, declared a disaster following an outbreak of bird flu at a commercial poultry facility in Weld County.

Data published by the U.S. Department of Agriculture show that about 1.8 million chickens were affected by avian influenza in the county in recent weeks. Neither Mr. Polis’s office nor the USDA provided information about the affected commercial poultry facility.

The emergency declaration means that Colorado can “take all necessary and appropriate state actions to assist with response, recovery, and mitigation efforts,” the governor added.

There is currently a “low” risk to the public posed by bird flu, the CDC said, adding that “there are no signs of unexpected increases in flu activity otherwise in Colorado” and in other states affected by H5N1 outbreaks in commercial flocks or cows.

But the agency noted that human infections with a “novel influenza virus” such as H5N1 are of concern because it can lead to severe disease and has the “potential” to trigger a “pandemic.”

“If these viruses were to change to spread easily from person-to-person,” the CDC wrote, “it could trigger a pandemic, though, to date, we have not seen genetic changes in the virus that would make it more likely to transmit between humans.”

Its recommendations in connection to avian influenza haven’t changed with the new Colorado cases, the CDC said, but an investigation will reveal whether changes to CDC guidance are needed in the future.

Aside from the three cases referenced by the CDC, a human H5N1 case in Colorado was detected in 2022 in someone who was exposed to infected birds, officials say.

In 2024, three other dairy workers have been infected with the virus, with one case in Texas in April and two cases confirmed in Michigan in May. Two infected individuals reported conjunctivitis, while one reported having a cough and eye discomfort with a watery discharge.

“Historically, most human cases of bird flu infection have happened in people who are not wearing recommended personal protective equipment,” the CDC stated on July 12. “An analysis of the virus sequences from this outbreak also will be important to determine if a change in the risk assessment is warranted.”

The U.S. Food and Drug Administration, in a recent study, confirmed that “the most commonly used pasteurization time and temperature requirements were effective at inactivating” the virus.

The agency recommended in April that dairy companies not sell or manufacture raw milk products from cows showing signs of illness, including cows that were infected with avian influenza viruses or exposed to infected cows.