Bird flu cases are still rising in the U.S. as the virus continues to devastate poultry farms. More than 145 million chickens, ducks, turkeys and other fowl have been slaughtered across the United States since the outbreak began in January 2022. As for humans, 67 people have been infected, according to the Centers for Disease Control.

First U.S. detection of virulent H5N9 strain, at a California duck farm, draws scrutiny as evidence of genetic reassortment that could trigger human outbreaks.

The United States has reported its first outbreak of H5N9 bird flu on a duck farm in California, according to the World Organization for Animal Health (WOAH) on Monday. H5N9 is a rare subtype of the influenza A virus that can cause highly pathogenic avian influenza (HPAI),