Another dairy farm worker in Michigan has been infected with avian influenza virus, state and federal health officials reported Thursday.
The case marks the third time the outbreak of bird flu in milking cows is known to have spilled over to a human. The dairy farm worker in Michigan, like the others, had close contact with H5N1-infected dairy cows, suggesting another case of cow-to-human transmission.
But the case reported today is notable for being the first one involving respiratory symptoms. In the first two cases, the dairy workers (one in Texas, the other in Michigan) reported only eye infections (conjunctivitis). This third case—also in Michigan but from a different farm—reported upper respiratory symptoms, including cough, congestion, and sore throat, as well as eye discomfort and watery discharge, but not conjunctivitis. The worker was given an antiviral (Tamiflu) and is said to be recovering. No other workers on the farm have shown symptoms, and the worker's household contacts are being monitored.
In a statement Thursday, the chief medical executive for Michigan's health department, Natasha Bagdasarian, explained that the latest case appeared to have a different exposure than the previous case in the state.
"With the first case in Michigan, eye symptoms occurred after a direct splash of infected milk to the eye," Bagdasarian said. "With this [new] case, respiratory symptoms occurred after direct exposure to an infected cow. Neither individual was wearing full personal protective equipment (PPE)." Bagdasarian added that the state has "not seen signs of sustained human-to-human transmission, and the current health risk to the general public remains low."
In a call with journalists Thursday afternoon, Nirav Shah, principal deputy director for the Centers for Disease Control and Prevention, emphasized that respiratory symptoms are the norm for influenza virus infections in humans, including H5 infections. Though the respiratory symptoms are not surprising, he added that they do pose more risk than a person with an eye infection. "Simply put, someone who's coughing may be more likely to transmit the virus than someone who has an eye infection, like conjunctivitis," Shah said.
Between 2003 and April 2024, the World Health Organization documented 889 human cases of H5N1 in 23 countries, leading to 463 deaths, which indicates a 52 percent case fatality report.