Federal health authorities have confirmed at least three people in Washington have contracted bird flu after working around poultry with the virus at a commercial egg farm in Franklin County.

State and local health officials revealed four people in Washington were “presumptively” positive for the illness, based on initial testing at a state lab on Oct. 20. Since then, the number of positive cases has climbed.

The U.S. Centers for Disease Control and Prevention confirmed three of the positive tests and one case associated with the Washington poultry outbreak is pending jurisdiction assignment, according to a CDC Nov. 4 report. The CDC said some workers who tested positive reported mild upper respiratory symptoms.

Staff from the CDC were on site in Franklin County in late October. The federal agency, along with the state health department and the local health district for Benton and Franklin counties, were working together on testing and other response efforts.

Roberto Bonaccorso, a spokesperson for the state Department of Health, said health agencies are working to test more than 100 people. Some people will be tested more than once.

Washington is one of six states where bird flu has spread to people. The CDC has so far counted more than 30 human cases of the disease during 2024 in those states, including the three confirmed in Washington.

There is no evidence of human-to-human spread of the disease at this time – all identified infections are among workers who had contact with infected birds or their environments, the Washington State Department of Health said Oct. 24.

The department also said that no patients have experienced severe illness or been hospitalized. Infected individuals had shown signs of mild upper respiratory illness, including runny nose, sore throat, and mild cough, as well as conjunctivitis — often referred to as “pink eye.”

For now, risks from the disease for people who are not around animals that can catch it are considered low. But health officials are keeping watch for signs the illness may be evolving in a way where it can spread between people or cause more severe symptoms.

People who have tested positive in Washington were exposed to the outbreak among poultry at the egg farm in Franklin County. There, a flock of about 800,000 birds became infected with what is formally known as highly pathogenic avian influenza.

Testing in mid-October showed poultry on the farm were infected. Health officials arranged for testing on Oct. 18 of workers showing symptoms. Presumptive positive tests for people came back the next day.

Washington’s Department of Agriculture is also reporting bird flu detections in two small backyard flocks — one in Kitsap County on Oct. 17 and another in Lewis County on Oct. 23. The Lewis County incident is listed as “presumptive” by the department.

“Every backyard flock is at risk right now,” state veterinarian Amber Itle said in a statement. “Avian influenza is a very serious disease with serious implications for animal welfare. It’s crucial to stay alert for any sudden illness and deaths in your flock”

When poultry is suspected of having the virus, tests are run at the state level at the Washington Animal Disease Diagnostic Laboratory. Positive results are then confirmed by National Veterinary Services Laboratories.

Bird flu, which is relatively common in wild birds, spreads rapidly through poultry flocks, sickening and killing the animals. To stop the spread, birds are euthanized. Fall is a risky time of year for the disease in Washington as migrating birds pass through.

Since 2022, 48 commercial and backyard flocks in the state have been stricken with the virus, according to state department of agriculture figures. The October cases are the first ones recorded in 2024.

The agriculture department said that “humane depopulation” of the birds was complete at the Franklin County facility and that cleaning, disinfection, and disposal activities were underway. The plan was to destroy eggs on the farm as well.

Agriculture officials also said no infected birds or eggs have entered the food supply chain.

Monitoring of poultry in the area where the farm is located has been taking place. Dairy cows were being watched too since they’ve caught the virus in other states. On Oct. 24, the state agriculture department said there were no confirmed or suspected cases at Washington dairy farms.

The Tri-Cities Area Journal of Business contributed to this report.

This story is republished from the Washington State Standard, a nonprofit, nonpartisan news outlet that provides original reporting, analysis and commentary on Washington state government and politics.