Unlike the previous two cases, in which the workers mainly experienced conjunctivitis, this most recent case experienced respiratory symptoms including “a cough, congestion, sore throat and watery eyes.” 

“With the first case in Michigan, eye symptoms occurred after a direct splash of infected milk to the eye. With this case, respiratory symptoms occurred after direct exposure to an infected cow,” Natasha Bagdasarian, Michigan’s chief medical executive, said in a statement.   

The case does not change the Centers for Disease Control’s (CDC) bird flu human health risk assessment for the general public, officials said, because all three cases had direct contact with infected cows.   

There’s no evidence yet that the virus is spreading between humans, but a virus in the airway can spread much more easily than an infection in the eye, the CDC’s principal deputy director Nirav Shah told reporters Thursday. 

“What the respiratory symptoms tell us more than anything, is that this virus like many viruses can present in more than one way. And for that reason, we should remain alert, not be alarmed,” Shah said.   

Both cases in Michigan were found because officials were actively monitoring farmworkers for symptoms. Still, public health experts have expressed concern that not every state is as vigilant, so cases are likely being missed.  

Neither farmworker was wearing full personal protective equipment (PPE). Officials stressed that PPE is an important tool in preventing spread among individuals who work on dairy and poultry farms.