New strain of bird flu found in California: Current status in maps
A new bird flu (highly pathogenic avian influenza) outbreak has been discovered in California.
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.
As the number of U.S. bird flu cases steadily increases, whole poultry farms have been wiped out in efforts to control the virus.
Human cases of bird flu in the US
To date, 60% of human illnesses have resulted from contact with cattle sickened by birds, according to the Centers for Disease Control and Prevention. Approximately a third have been linked to culling operations or exposure to chicken farms. Of the more than 600 people exposed to infected animals, 67 tested positive for the disease since 2024.
One person infected with the bird flu died on Jan. 6 in Louisiana. The patient was over 65 and became ill after contact with a combination of a backyard flock and wild birds, the Louisiana Department of Public Health said.
Unable to view our graphics? Click here to see them.
Impact of bird flu on poultry farms in the US
During the past three years, bird flu has been reported in more than 145 million birds in 618 counties and all 50 states, according to CDC data as of Jan. 24.
The CDC recommends people such as backyard flock owners, hunters and bird enthusiasts take extra precautions if they work around or have recreational exposure to birds or farm animals.
Impact of cattle farms in the US
The bird flu has spread through dairy cattle throughout the U.S. and has led to several human cases. Between October and December 2024, when the number of cases in birds began to increase, the majority of cases in cattle – 673 out of 929 – were found to have the disease, according to USAFACTS.
States affected by bird flu cases in cattle herds
Since the beginning of 2024, 77% of all cases of avian flu in cattle have occurred in California.
What are the symptoms of bird flu in humans?
While it's still uncommon for bird flu viruses to jump to humans, humans can contract the disease through the mouth, eyes, or nose. In some cases, people have inhaled the virus after coming into contact with an infected animal.
◾ Symptoms can be mild: fever, cough, sore throat, body aches, eye infections ((conjunctivitis, or pinkeye), runny or stuffy nose, fatigue and muscle aches.
◾ Symptoms can be severe: shortness of breath, high fever (100 degrees or higher), pneumonia (requiring hospitalization) and severe repertory disease.
CONTRIBUTING Fernando Cervantes Jr. and Jim Sergent
SOURCE Centers for Disease Control and Prevention, U.S. Department of Agriculture, World Organization for Animal Health, Newsweek, USAFACTS.org and Paste BN research
This story was updated to add new information.