Bird Flu Symptoms: New Strain Discovered In CA As Outbreaks Spread

CALIFORNIA — A new highly pathogenic strain of the bird flu has been discovered in California, raising alarm bells for agricultural and health officials in a state that has suffered the most outbreaks — human, bovine and avian — nationwide.

The major concern about the virulent variant — H5N9 — is that it could lead to more outbreaks on chicken farms and dairies as well as accelerating the pace of bird flu mutations. The strain was reported last week on a California duck farm where the birds also contracted the predominant variant — H5N1. Mutant strains can emerge when two variants of a virus combine, potentially creating strains that pose a larger threat to humans.

At this time, experts say bird flu poses very little risk and is very rare for humans, but it did kill one person in the U.S., officials confirmed on Jan. 6. Since the outbreak began in the spring of 2022, 38 of the nation's 67 human cases, have occurred in California, according to the Centers for Disease Control and Prevention.

Experts say how much we should really worry about bird flu will depend on two factors — how the virus mutates as it spreads and the development of new vaccines.

Here are five things to know about bird flu in California:

What do we know about the new strain in California?

Health officials such as Rais Vohra, a professor at UC San Francisco and interim health officer for the Fresno Department of Public Health, are monitoring the mutation closely.

According to Vohra, H5N9 could be more virulent for birds and other farm animals, but currently, it doesn't pose a greater risk to humans.

The main concern, according to Vohra, is how it will evolve as it spreads: "It's evolution alongside seasonal flu and other strains, could, in the future, produce new versions of the virus that spread more easily among humans."

Richard Blatchford, Associate specialist of Cooperative Extension at the UC Davis College of Agricultural and Environmental Sciences and an expert on the welfare of small-to-large-scale poultry production, echoed that sentiment.

"Every time it infects an organism, it mutates," he said. "And so the worry is generally that the more it infects mammalian species, the more likely it is to become a virus that is much more like the flu viruses that we already contract and can spread from person to person."

On Wednesday, the CDC briefly posted data showing apparent cases of a bird flu appearing to spread among between cats and humans in two households, but the report was quickly pulled from the website, according to The New York Times and Washington Post, which kept screengrabs of the data before it was culled from the site.

The data about the bird flu potentially spreading between cats and humans appeared to have been mistakenly buried in a report about the health impact of the Los Angeles wildfires, the newspapers reported. Scheduled CDC updates on the spread of bird flu have not been released since the Trump Administration instructed federal health agencies to pause external communication on the president's first day in office, the Washington Post reported.

The spread of bird flu has been concerning. Outbreaks have spread from remote farming communities to the more populous part of the state, with outbreaks in Southern California's Inland Empire. Infected migratory birds can spread the disease via feces.

"We’ve never seen a global spread of avian influenza virus like this,” Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota told Time. “We’ve seen an explosion in the number of outbreaks in poultry and duck operations over the course of recent weeks. This reflects the fact that there is so much H5N1 in migrating waterfowl."

What are the symptoms of Bird Flu?

While many upper respiratory symptoms of bird flu mirror other types of influenza, there is one telltale sign that doctors look out for.

"The trademark symptom of bird flu infection is conjunctivitis or pink eye," said Vohra. "When I’m consulted about a potential case of the bird flu, I ask two questions: Does the patient have pink eye, and Do they work in the dairy or poultry industry?"

Other symptoms include mild, flu-like congestion, pneumonia, fever or feeling feverish, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, fatigue, shortness of breath or difficulty breathing, according to Vohra.

Less common symptoms include diarrhea, nausea, vomiting and seizures.

What risk does bird flu pose for humans?

The first known bird flu case was reported in Hong Kong in 1997, according to the National Library of Medicine. Since 2003, more than 23 countries have reported more than 880 human infections with bird flu viruses, according to the World Health Organization.

It's important to note that bird flu has never been known to pass from person to person. Those who are most at risk are those who interact with infected dairy cows, poultry, or wildlife, according to California's health department.

Because it is a respiratory virus that is spread by breathing air containing viral particles of infected animals, the state says people who work with infected dairy cows or raw milk should use protective gear to reduce the risk of getting bird flu.

Sick farm cattle that have infected a growing number of humans in the Central Valley and a recent spate of domestic cat deaths have elevated some concern among experts.

"Avian diseases tend to be hard to contract for mammals because our physiology is just very different," Blatchford said. "Because this is showing up in lots of mammals now, it makes a little bit more worrisome — but not something that people should be day-to-day worried about."

Most of the recent human cases in California are among people who have spent long periods with dairy cattle and other sick or dead infected birds. But there have been some human infections that had unknown roots.

How do we control bird flu?

To date, control measures have included rapid euthanasia of infected chicken flocks. But the disease has been spreading to mammals, including humans. More recently, the disease began killing domestic cats.

Blatchford says we're in "unknown territory."

"The way that avian influenza is controlled in poultry is by rapid euthanasia of any flock that tests positive, and oftentimes flocks that are presumed to be positive," Blatchford said.

The 2024 outbreak saw the euthanasia of approximately 40 million birds nationally and 17 million in California, leading to significant scarcity. Normally, there are about 300 million laying hens nationwide that keep up with egg demand, Blatchford said.

Since avian flu quickly kills birds within 24 to 48 hours, euthanasia is considered the most humane and effective way to keep the spread at bay, Blatchford said. But with no signs of the outbreak slowing, experts remain concerned about long-term effects on poultry supply and food prices.

What's more, the outbreak took an unexpected turn when cattle started becoming infected.

Since cattle are much more expensive than hens tend to be and they don't become as sickened as birds, cattle are generally treated before they are released back into their herd. The next step in terms of biosecurity could be an avian flu vaccine for livestock, Blatchford speculated.

But even that solution could come with trade complications, he said.

That's because countries, including the U.S., do not accept products that test positive for bird flu and there would be no way to differentiate between the antibodies given from a vaccine and an infection.

"There's a huge economic component there," he said.

Additionally, prices for a regular carton of eggs have hit an all-time high in California. And those prices could continue to climb as H5N1 avian influenza — or bird flu — continues to bedevil farms, backyard poultry at a rate never seen before.

The outbreak began picking up steam in the Golden State over the last year

When was the last bird flu outbreak in U.S.?

In 2015, the U.S. experienced its last significant bird flu outbreak, which was mostly contained in the Midwest. That year, prices did rise slightly as flocks were euthanized. But Blatchford says that outbreak pales in comparison to the one that's been plaguing the U.S. since 2022 and particularly California.