A Colorado man has tested positive for avian influenza, also known as bird flu, the first case identified in the nation from a recent outbreak that has caused widespread quarantines and culling of poultry flocks across the globe.
A state health official says the risk to the public is low and that the virus is unlikely to spread person-to-person.
The man was working at a commercial poultry farm in Montrose County, according to the Colorado Department of Public Health and Environment. He tested positive earlier this week in a single sample taken from his nose. The federal Centers for Disease Control and Prevention confirmed the result on Thursday.
CDPHE said that, because the man had been in close contact with infected poultry, it is unclear whether he had a full-blown infection. “Colonization,” when virus particles first enter the nose, is sometimes but not always a prelude to an infection.
The man is isolating and is asymptomatic other than feeling fatigued. He is taking the antiviral drug tamiflu.
“This is not surprising that this detection has occurred,” Dr. Rachel Herlihy, the state epidemiologist, said. “We know that unfortunately we are seeing widespread transmission of this virus in wild birds and also domestic birds. We know there are a large number of individuals working closely with these birds.”
The Colorado man is the second person worldwide to test positive for the particular strain of H5N1 influenza that is responsible for the current outbreak. The first person, a retired engineer in the United Kingdom who lived with about 20 ducks inside his home, tested positive late last year.
Herlihy said the fact that both people worked closely with birds shows the unlikelihood of the virus jumping easily between birds and people. She said there is also no evidence so far of person-to-person transmission for the current avian influenza virus. Previous strains of H5N1 flu have produced only limited, non-sustained transmission between people.
“Overall, the risk to the U.S. public from this virus is low,” Herlihy said. “There is obviously greater risk among individuals who have close or prolonged contact with birds.”
The Colorado man is an inmate at a state correctional facility in Delta County, according to CDPHE. He was working at the poultry farm as part of a pre-release employment program, and had been provided with personal protective equipment.
The affected flock at the farm has been euthanized.
Herlihy said the state has detected avian influenza in both wild and domestic birds. She said people should avoid having contact with birds, especially ones that are dead or appear sick, and should also avoid surfaces soiled with bird feces. People who must be in contact with birds should wear gloves, a respirator face mask and eye goggles, and they should wash their hands thoroughly with soap and water afterward.