A person in Louisiana has the first severe illness caused by bird flu in the U.S., health officials said Wednesday.The patient had been in contact with sick and dead birds in backyard flocks, the Centers for Disease Control and Prevention said. Agency officials didn't immediately detail the person's symptoms.Previous illnesses in the U.S. had been mild and the vast majority had been among farmworkers exposed to sick poultry or dairy cows.This year, more than 60 bird flu infections have been reported, with over half of them in California. In two — an adult in Missouri and a child in California — health officials have not determined how they caught it.The CDC confirmed the Louisiana infection on Friday, but did not announce it until Wednesday. It’s also the first U.S. human case linked to exposure to a backyard flock, the agency said.The Missouri patient also was hospitalized, but for reasons beyond just the bird flu infection. The Louisiana case is different because the person's hospitalization is due to the flu symptoms, CDC officials said.Did the Louisiana patient have pre-existing conditions that made him or her more susceptible to illness? Is the person on a ventilator? The CDC deferred those and other questions about the patient to state health officials, who did not immediately respond.Last month, Canadian officials reported that a teen in British Columbia was hospitalized with a severe case of bird flu. CDC officials did not answer a question about whether the new U.S. case had any similarities or differences, directing reporters to ask Louisiana officials.Health officials say bird flu is still mainly an animal health issue, and the risk to the general public remains low. There’s been no documented spread of the virus from person to person.