Third Bird Flu Infection in the U.S. Shows Respiratory Symptoms

A third dairy worker in the U.S. has tested positive for the bird flu infection which is causing outbreaks in cattle in at least .

The farmworker, from Michigan, was exposed to infected cows and is the first case of the bird flu infection in the U.S. to cause respiratory symptoms, according to the Michigan Department of Health and Human Services. The previous two people—another in Michigan and one in Texas—did not show any respiratory symptoms but experienced discharge from the eyes. The dairy worker in the latest case worked on a different farm in Michigan than the previous case reported in the state.

According to the U.S. Centers for Disease Control and Prevention (CDC), the dairy worker in the latest case also tested positive for influenza A(H5), the avian influenza strain, and reported coughing (with no fever). Tests on samples from the patient performed by Michigan’s health department were positive for influenza A(H5), the avian influenza strain. Further tests conducted by CDC scientists confirmed the results.

It’s not clear whether the respiratory symptoms indicate that the virus is changing; CDC scientists are conducting additional sequencing studies to determine if that’s the case.

The CDC says there are no spikes in influenza cases among people in areas where the virus has been reported in cows, nor are there any unusual increases in emergency room visits or positive lab tests for influenza. So far, there have also been no reports that the virus was spread from one person to another in the infected workers’ households. In all three cases, the infected workers, as well as their families, were monitored and offered antiviral medications.

For now, the agency says the outbreak in cows does not pose a significant health threat to people who don’t routinely work with the animals. Those who do, however, should wear protective equipment and practice caution when handling sick or dead animals, including birds and cows, as well as monitor and report any flu-like symptoms to their local health department.

Everyone should also avoid raw milk, which has not been pasteurized, the CDC advises. The temperatures required for pasteurization generally inactivate the virus, so pasteurized milk remains safe to drink, according to the agency.