A new strain of bird flu has been detected on a duck farm in California. The World Organisation for Animal Health reported the outbreak of the new strain, H5N9, earlier this week.

The California duck farm's strain of H5N9 is different from those earlier cases because this time it is closely related to a newer variant of the H5N1 virus. That variant is called H5N1 D1.1, the USDA spokesperson said, which has emerged over the past year to dominate U.S. cases in wild birds and poultry.

In related developments, West Virginia officials suspended poultry exhibitions and Massachusetts warned of sick and dead birds across several cities.

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.

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.

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.

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.

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

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.

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.

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.