By India Edwards HealthDay Reporter WEDNESDAY, Jan. 29, 2025 (HealthDay News) -- A new strain of bird flu, H5N9, has been detected for the first time in the United States, raising concerns about how it continues to spread.

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

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.