Three workers at a Colorado egg farm contracted mild cases of bird flu while culling an infected flock of chickens, said state public health officials. With the discovery, Colorado is home to four of the seven U.S. cases of bird flu in humans reported since April.
The Centers for Disease Control said it would conduct testing of samples from the Colorado workers to confirm the results and send a team to Colorado to support the state’s investigation. The risk of the avian flu virus to the general public remained low, said the CDC. Public health officials monitor the cases because of the possibility the virus might evolve and become more infectious to people.
“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 of the individuals were hospitalized,” said the Colorado state Department of Public Health and Environment on Friday.
A dairy farmworker, also in northeastern Colorado, developed a case of avian flu earlier this month, apparently from direct exposure to infected cows. He was treated with an antiviral medication for symptoms limited to pink eye and recovered.
Two dairy farmworkers in Michigan and one in Texas also have developed mild cases of bird flu.
The H5N1 avian flu virus has killed more than 99 million birds in domestic flocks since it appeared in the United States in February 2022, according to a USDA database. Infections have been reported in 152 dairy herds in 12 states since bird flu was identified in March as the mysterious disease circulating in dairy herds in the Texas panhandle.
Colorado has the largest number of infected dairy herds in the nation, 35, followed by Idaho with 28 and Michigan with 26, according to USDA. Some 8.1 million birds in Colorado flocks have died of highly pathogenic avian influenza since February 2022.
In May 2022, the CDC said a Colorado correctional inmate tested positive for bird flu after culling an infected flock. It was the first U.S. case and the second worldwide of human infection by the H5N1 virus. The male correctional inmate was largely asymptomatic and reported fatigue after working, as part of a pre-release programs, at an egg farm in Montrose County, about 50 miles south of Grand Junction in the western part of the state.
The CDC suggests people avoid contact with sick animals and that workers wear protective equipment, such as masks, gloves and goggles, if they are in prolonged close contact with livestock that might be infected.
Over the weekend, the CDC updated its guidance to farmers to prevent the spread of avian flu between animals and people at agricultural fairs. “It is rare for people to get sick from these viruses, but when they do, the sickness has varied from mild to severe. In some cases, it has led to hospitalization or death,” said the federal agency.
As precautions, the CDC said exhibitors should keep pigs, poultry, and cattle at the fair for shorter times than usual — “72 hours or less is ideal;” not eat or drink while in show barns or arenas; wash hands often; avoid contact with pigs, poultry, cattle, and other animals that appear sick; and clean and disinfect all equipment and show supplies before and after the fair. “Do not share equipment used for other animals,” it said.