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.

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.

Turkeys in a commercial Sampson County flock have tested positive for highly pathogenic avian influenza, the N.C. Department of Agriculture announced Tuesday.

British health authorities said on Monday they had detected a case of the H5N1 bird flu in a person in central England but added that the risk to the wider public remained "very low".

The first case of bird flu on a farm in Pennsylvania in 2025 was detected on a poultry farm in Lehigh County on Monday, the state's Department of Agriculture announced.