The newly reported H5N9 strain was found Monday at a duck farm in Merced County, California, according to the World Organization for Animal Health. The Paris-based organization that studies animal diseases said it's the first verified U.S. case of H5N9 in poultry. The organization said the more common strain H5N1 was also found.

This week, the World Organization for Animal Health reported that it had been notified by the USDA that a November outbreak of highly pathogenic avian influenza on a California duck farm was caused by a strain not before seen in the United States: H5N9.

According to the Centers for Disease Control and Prevention, bird flu outbreaks have impacted poultry in 51 states, while the virus has been detected in dairy cows across 16 states.

Both H5N9 and H5N1 were detected at the duck farm in Merced County, according to tests conducted by the US Department of Agriculture (USDA) National Veterinary Services Laboratory. The event began on November 23, with clinical signs that included increased deaths in the ducks.

A new strain of H5N9 bird flu was detected at a commercial duck operation in California's Merced County. All the ducks were euthanized.

Learn about the new H5N9 bird flu strain in the US, its impact on food safety and prices, plus expert advice on protecting yourself from avian influenza.

Rose Acre Farms, the nation's second largest egg producer, said yesterday that tests have confirmed avian flu at its facility in Seymour, Indiana, which could further stretch the supply of eggs as commercial farms in several states continue to battle the spread of the H5N1 virus.

Minnesota and Iowa were added to the National Milk Testing Strategy on Jan. 8. There are now 36 states involved in the testing for the avian influenza virus.

The H5N9 strain of avian influenza is much more rare than the H5N1 which has been responsible for most of the reported human cases and the first human death.

Commercial duck flock in California has tested positive for two strains of avian influenza. On November 23, 2024, two HPAI viruses were identified in samples from a farm rearing meat ducks in Merced County in California. Increased mortality was observed at the premises, leading the state veterinary authority to quarantine the farm.

The United States has reported its first H5N9 bird flu outbreak in California, affecting almost 119,000 ducks. Both H5N9 and the more common H5N1 stra