Health officials announced Wednesday the patient had been in contact with sick and dead birds in backyard flocks, the Centers for Disease Control and Prevention said. Previous illnesses in the U.S. had been mild and the vast majority had been among farmworkers exposed to sick poultry or dairy cows. 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. 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.