For the past three years,a novel form of bird flu has wiped out millions of animals in the United States, from snow geese to backyard chickens.

But conversations around the outbreak have grown more urgent in recent months, as Louisiana recorded the country's first human death from bird flu in January and the death toll for animals continues to rise.

In Washington, about 2.2 million commercial, backyard and wild birds have tested positive for Type A H5N1 influenza, including 52 backyard flocks and three commercial ones. About 14 Washingtonians — all commercial farmworkers — have tested presumptively positive since 2022.

While the risk to the general public remains low, state epidemiologist Dr. Scott Lindquist urges people to take the virus seriously. There’s still a chance it could mutate and become more infectious to humans, he said.

“We are not seeing that yet — but that’s the concern,” Lindquist said.

Here are some basics about the outbreak and potential risks:

When did bird flu begin?

The first case of bird flu was documented in 1878 in northern ​​Italy and was called the “fowl plague,” according to the U.S. Centers for Disease Control and Prevention. In 1955, scientists discovered the illness is caused by a Type A influenza virus. Most cases were mild or “low pathogenic,” and birds showed few to no symptoms.

In 1996, “highly pathogenic” avian influenza emerged on a goose farm in Guangdong province, China, killing 40% of the flock. Between 1996 and 2005, migrating birds carried the virus across Asia, Africa and Europe. HPAI is now circulating freely (endemically) between farms and wild populations.

What do symptoms look like?

Sick birds can experience mild signs of respiratory disease, including sneezing, discharge from the eyes, ruffled feathers, lethargy, and a decrease in appetite and egg production, among other symptoms. Mammals often develop neurological symptoms, while people can experience pink eye (or conjunctivitis), fevers, coughing, headaches, muscle pain or sore throat.

How are different animals infected?

The virus spreads through contact with contaminated surfaces or infected animals’ saliva, mucus or feces. The virus can also be transmitted through consumption of infected animal meat or raw milk. It works its way up the food chain, infecting small mammals when they prey on sick birds, then top predators that eat smaller mammals.

Is it safe to eat animal products?

Chicken, eggs and other poultry products are safe to eat when properly handled and cooked. Milk is safe to drink when pasteurized, but consuming raw, unpasteurized milk and raw animals can be a risk to humans and pets.

Eating raw pet food can also be dangerous for animals. Last week, a domestic cat in Washington was euthanized after eating potentially contaminated pet food and getting sick, similar to other indoor cat infections nationwide.

How can I prevent infection among my birds?

If you have a backyard or commercial flock, try to limit contact between your birds and outside visitors or animals. Keep poultry separate from wild waterfowl. Keep shoes, clothes and other equipment clean.

How can I best avoid getting infected?

Wash your hands and wear personal protective equipment when around wild or domestic birds, Lindquist said. Avoid direct contact with sick or dead animals. And although getting vaccinated against seasonal influenza doesn’t prevent bird flu infections, it can reduce the chances of becoming simultaneously infected and giving the virus an opportunity to mutate, Lindquist said.

Where can I get tested for bird flu?

The CDC recommends that people with recent exposure to bird flu reach out to their health care provider or local public health department to get tested.

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