Avian flu confirmed in a Colorado farmworker, marking fourth human case in U.S. since March

A case of H5 influenza, also known as bird flu or avian influenza, has been confirmed in a man who was working at a dairy farm in northeastern Colorado. That's according to the Colorado Department of Public Health and Environment, which said it is the fourth confirmed human case in the United States since an outbreak among cows that appears to have started in March.  

The man was working in Northern Colorado and had direct contact with cattle that were infected with avian flu. To this point, the only U.S. cases have been among farmworkers.

The CDPHE says the person who tested positive for the avian flu only had one symptom — pink eye, otherwise known as conjunctivitis.

The CDC, however, reported Friday that a "respiratory sample," from the worker also tested positive for the virus, despite the patient not reporting symptoms other than pink eye. So far, only someone in Michigan — who was also exposed to sick dairy cattle — has developed respiratory symptoms after being infected with the virus.

The Colorado worker was tested after reporting his symptoms and received an antiviral treatment with oseltamivir afterwards. Those are the Centers for Disease Control and Prevention's recommended steps when there's a confirmed human case. The man, whose identity is not being released, has recovered.

This is the first confirmed a case of avian flu in Colorado since 2022. CDPHE state epidemiologist Dr. Rachel Herlihy said the risk to the public is low.

"Avian flu viruses are currently spreading among animals, but they are not adapted to spread from person to person. Right now, the most important thing to know is that people who have regular exposure to infected animals are at increased risk of infection and should take precautions when they have contact with sick animals," Herlihy said in a prepared statement.

Jill Hunsaker Ryan, the executive director of the CDPHE said "Coloradans should feel confident that the state is doing everything possible to mitigate the virus." The guidance for farmworkers includes the recommendation that people shouldn't touch animals who are sick or who have died. For people who must handle such animals, the following is recommended:

- Wear personal protective equipment that includes an N95 respirator as well as eye protection and gloves.
- Wash hands with soap and water afterward. An alcohol-based hand rub could also be used if soap and water is not available.

"We can make these recommendations, but I think all of us realize that this may be a bit challenging for workers to comply with that," the CDC's Tim Uyeki said at a briefing with rural doctors last month.

It is unclear whether the man was wearing personal protective equipment.  

"Our partnership with the Colorado Department of Agriculture has been crucial in disseminating information to dairy farmers across the state," Hunsaker Ryan said.

The three other confirmed human cases of avian flu since the March outbreak in cattle were found in Texas and Michigan. 

Anyone who has been working with dairy cows and begins to feel sick with possible avian flu symptoms should call the CDPHE at 303-692-2700 during the day or 303-370-9395 after hours.

More information about avian flu can be found on the Colorado Department of Public Health and Environment's website.

News of the case comes as federal officials are now debating whether and when to deploy 4.8 million doses of bird flu vaccine that are being filled into vials this summer. Finland announced last month it would offer shots to workers who might be exposed to the virus.

Vaccinating farm workers?

U.S. officials say manufacturing of the vaccines is expected to be done by August. 

Vaccinemaker CSL Seqirus says it is still in talks with the Food and Drug Administration to clear use of their shots in humans. After that, it would be up to the CDC to decide whether to roll out the shots for farm workers.

"No final decisions are made, but we are in the process of robust discussion," the CDC's Principal Deputy Director Dr. Nirav Shah told reporters on Tuesday. 

Shah said the vaccine debate hinges in part on whether more distribution of flu treatments might be a better alternative.

"If our goal is to reduce the number of infections that may occur, we have to wonder whether vaccination is the best route for that, or whether there may be other routes that are faster or even more effective such as, as I mentioned, more widespread use of antivirals," said Shah.

Officials are also discussing other measures to help workers infected with the virus, Shah added, including the possibility of offering financial help with sick leave and further outreach.

Farm workers may also not be willing to get the shots, even if they were to become eligible for vaccination.

"If right now, H5 is not perceived as a pressing threat among farm workers, and I'm not speculating as to whether it is or not, but if that is the case, then uptake may not be robust," said Shah.