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.

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