MERCED COUNTY, Calif. (KSEE/KGPE) – The country’s first case of H5N9 bird flu has been identified in Merced County, California, officials say.

This H5N9 strain, which was identified earlier this month, is different from the H5N1 strain that had already been documented in multiple cases across the U.S. According to the Centers for Disease Control and Prevention, there have been more than 60 people who have been sickened and one person who was killed by H5N1.

In a notification, the World Organisation for Animal Health confirmed that the strain detected in Merced County is a new strain in the country. The investigation began on Nov. 23, 2024, and it was confirmed on Jan. 13 that “this is the first confirmed case of HPAI H5N9 in poultry in the United States.”

The USDA Animal and Plant Health Inspection Service (APHIS), in conjunction with State Animal Health and Wildlife Officials, are conducting comprehensive epidemiological investigations and enhanced surveillance in response to the HPAI related events.

World Organisation for Animal Health

This strain of H5N9 was found in a commercial duck premises in Merced County. The specific location of the facility was not officially released.

The announcement states that control measures have been undertaken in an attempt to contain the virus, including control of movement, surveillance and quarantine. The report from the World Organisation for Animal Health also stated that a total of 118,954 birds were killed in December after state officials quarantined the affected area.

Bird flu is primarily spread by wild birds such as ducks and geese as they migrate. While it is fatal to a variety of animals, those species can generally carry it without getting sick, which offers the virus a chance to mutate and thrive.

The virus can be spread through droppings or any interaction between farm-raised poultry and wild birds. It’s also easily tracked into a farm on someone’s boots or by vehicle.

Unlike previous outbreaks, the one that began in 2022 didn’t die out in high summer temperatures.

The virus found another new host when dairy cattle started getting sick last March. That creates more opportunities for the virus to linger and spread and unlike poultry, cattle aren’t slaughtered when they get sick because they rarely die from bird flu.

Nearly all of the people infected with bird flu worked around sick animals. Health officials haven’t yet found evidence of the disease spreading from person to person.

The Associated Press contributed to this report.