A farmworker in Michigan is the second human to be infected with the current H5N1 bird flu virus, health officials said.
The farmworker had mild symptoms and has since recovered, Michigan health officials said Wednesday. The virus has been circulating in dairy and poultry farms across the U.S. this spring, and the farmworker was in contact with dairy cattle presumed to be infected.
“The current health risk to the general public remains low,” Natasha Bagdasarian, Michigan’s chief medical executive, said in a statement. “We have not seen signs of sustained human-to-human transmission at this point. This is exactly how public health is meant to work, in early detection and monitoring of new and emerging illnesses.”
According to the Centers for Disease Control and Prevention (CDC), a nasal swab from the person tested negative for influenza in a state lab, but an eye swab from the patient was shipped to CDC and tested positive for influenza A virus, indicating an eye infection.
Federal health officials told reporters Wednesday the case was detected because they were looking for it and emphasized that farmworkers remain at elevated risk. As exposures increase, the risk of additional cases among humans increases, they said.
The Michigan farmworker was enrolled in the state’s active monitoring program, but officials wouldn’t say when the individual was tested or when the positive test was reported. The individual’s close contacts are being tested as well
The CDC received the sample on Tuesday night, confirmed the results on Wednesday, and then reported the results to the state that same evening, CDC principal deputy director Nirav Shah said.
He said it is notable that a nasal sample tested negative while an eye swab tested positive.
“That’s reassuring,” Shah told reporters. “It reduces the likelihood — it does not eliminate — but it reduces the likelihood of a respiratory route of transmission. The other thing that it underscores is the importance of PPE [personal protective equipment] barrier protection, in particular for the eyes.”
Since 2022, there have been two human cases related to bird and dairy exposure in the U.S. — one in Colorado in 2022 and one in Texas earlier this year.
Similar to the Texas case, the patient in Michigan only reported eye symptoms.
Bird flu was first detected in dairy cows in March, though data from viral samples showed it had been circulating in cattle for at least four months prior and was the cause of a drop in milk production.
The U.S. Department of Agriculture has confirmed outbreaks in 51 herds in nine states, including Michigan, which has reported 19 infected herds.
“Today’s news underscores the continued importance of limiting nonessential farm visits, including farm tours and field trips, as well as the use of personal protective equipment when working with livestock,” Michigan Department of Agriculture and Rural Development (MDARD) Director Tim Boring said in a statement.
Still, public health and infectious disease experts are concerned the United States is too limited in its testing, leaving an incomplete picture of the virus’s spread.
Farmers have been reluctant to allow federal health officials onto their land to test potentially infected cattle amid uncertainty about how their businesses would be impacted.
Farmworkers have also been reluctant to participate in screening, and experts said it’s likely due to a mix of fears over job loss, immigration status, language barriers and general distrust in public health systems.
“We’d like to be testing more people. And we’ve seen variable cooperation among farmworkers, as you would see with any slice of people in the general population,” Shah told reporters Wednesday. “Some folks are more willing to chat with public health and be tested … we’ve seen a degree of cooperation across the country. We’d like for that to be as high as possible.”
Updated at 5:46 p.m.