The Centers for Disease Control and Prevention Dec. 18 announced that a patient in Louisiana was hospitalized with a severe case of H5N1 bird flu, the first known instance of severe infection in the U.S. The agency said the patient was exposed to sick and dead birds in backyard flocks and that an investigation is ongoing. It is the first case linked to backyard flock exposure, as most have been linked to daily dairy cows and poultry. 

There have been 61 reported human cases of H5N1 bird flu in the U.S. since April. The CDC said the immediate risk of bird flu to the public remains low.