A person in Louisiana has the first severe illness caused by bird flu in the U.S., the Centers for Disease Control and Prevention announced Wednesday.

Officials determined the patient had exposure to sick and dead birds in backyard flocks, though an investigation into the source of the infection in the state is ongoing. This is also the first case of H5N1 bird flu in the U.S. that has been linked to exposure to a backyard flock, a news release noted. Officials have not shared details on the patient’s symptoms. 

The case was first confirmed by health officials Friday, adding to the total of 61 reported human cases of H5 bird flu reported in the United States. Another severe case of H5N1 has been reported in a teen in British Columbia.

A release from the Louisiana Department of Health Wednesday added the patient, a resident of southwestern Louisiana, is currently hospitalized. Until now, the H5N1 cases in the U.S. have been mild, including conjunctivitis and upper respiratory symptoms. 

“While the current public health risk for the general public is low, people who work with birds, poultry or cows, or have recreational exposure to them, are at higher risk,” the state’s health department added.

Mild illnesses have been seen in dairy and poultry workers who had close contact with infected animals. In two cases, no known source of the illnesses have been identified, which has worried infectious disease experts about the possibility of human-to-human transmission, which could trigger a pandemic.