Dec. 18 (UPI) — A person in Louisiana became the first to be diagnosed with a severe case of the bird flu after possibly being exposed to sick and dead birds on their property, the Centers for Disease Control said on Wednesday.

A CDC official said it was unusual for someone to be exposed from the backyard flock in the United States.

“It is believed that the patient that was reported by Louisiana had exposure to sick or dead birds or their property,” Dr. Demetre Daskalakis, director of the National Center for Immunization and Respiratory Diseases, told CNN. “These are not commercial poultry and there was no exposure to dairy cows or their products.”

Those who have contracted the bird flu in the United States have been connected to sick poultry or dairy cows and most of the cases have arisen among farmworkers. Those cases had all been mild in nature, officials said.

Of the more than 60 bird flu infections in the United States this year, more than half have been in California. Health officials have failed to identify how two people — an adult in Missouri and a child in California — caught the disease.

In November, the CDC confirmed the first child contracting the disease. The agency said a child in California’s Alameda County tested positive for the disease despite no known contact with infected animals.