A farmworker was infected with bird flu from a dairy cow, the third human case in the recent outbreak.

A farmworker was infected with bird flu from a dairy cow, the third human case in the recent outbreak. / AP

Updated 3:10 p.m. ET

Michigan’s health department announced Thursday a human case of bird flu in a dairy worker. It’s the third human case reported to date in the current U.S. avian flu outbreak among dairy cows.

Unlike the previous two cases which only involved eye infection, this patient has respiratory symptoms, according to a statement from Dr. Natasha Bagdasarian, chief medical executive with the Michigan health department. The patient had direct exposure to an infected cow and wasn’t wearing any personal protective equipment.

“This tells us that direct exposure to infected livestock poses a risk to humans,” said Bagdasarian.

The Centers for Disease Control and Prevention said in a statement that its labs tested a sample from the Michigan patient and confirmed it was H5N1 bird flu. The patient had flu-like symptoms, including a cough and eye discomfort. The patient was treated with antivirals and is isolating at home. No other workers or household contacts of the patient have gotten sick so far.

The CDC said that risk to the general public remains low. Like the other two recent cases, this infection came from direct exposure to an infected animal. “There is no indication of person-to-person spread of A(H5N1) viruses at this time,” according to the CDC.

The CDC is monitoring data from influenza surveillance systems, and said “there has been no sign of unusual influenza activity in people.”

Nonetheless, scientists following the outbreak say this human case is troubling development.

“Our concerns about this outbreak are coming true,” says Dr. Rick Bright, a virologist and the former head of the Biomedical Advanced Research and Development Authority (BARDA). “The longer the U.S. allows this outbreak to continue, without appropriate measures to stop it, without conducting testing in cows and people, more people will be at increased risk for exposure and infection.”

Bright says it’s a problem that there's not better sharing of bird flu data in the U.S., and there’s not more testing and precautions to prevent spread. He warns this will lead to more humans infected by animals. And that could eventually lead the virus to adapt itself to spread among humans. “This virus will find a way to transfer more efficiently among humans. This is what happens with a virus like this,” he told NPR.

Both the CDC and Michigan health officials emphasized the importance of protecting farm workers from possible exposure.

Michigan Department of Agriculture and Rural Development director Tim Boring said his department is offering support to dairy farms in need of protective gear. "Proper use of personal protective equipment is the best tool we have to protect farm workers."

Will Stone contributed to this report.