• A bird flu outbreak has ravaged the world's birds since 2020 and infected cattle earlier this year.
• California Gov. Gavin Newsom declared a state of emergency over the virus this week.
• Health officials also confirmed the first "severe" case of and hospitalization for the H5N1 virus.

The burgeoning global bird flu outbreak continued its flight path across the country this week, with two major developments that point to the virus's increasingly concerning spread.

California Gov. Gavin Newsom declared a state of emergency over the virus on Wednesday, citing a worrying number of infected herds throughout the state in recent months and a need for more resources.

Since the state first identified the H5N1 avian influenza virus in cattle in late August, California's agriculture department has confirmed 645 infected dairy herds.

Newsom's announcement, meanwhile, came just hours after health officials confirmed the first severe case of bird flu in Louisiana, saying a person was hospitalized with an infection after being exposed to sick birds in his backyard.

In recent months, infectious disease experts have grown more and more nervous about the possibility of a human pandemic linked to the virus, even as the Centers for Disease Control and Prevention has maintained that the public health risk for humans is low.

Here's where things stand.

Bird flu outbreak

The H5N1 virus first reemerged in Europe in 2020 and has since become widespread in birds around the world. The outbreak has killed tens of millions of birds and tens of thousands of sea lions and seals in recent years.

Birds carry the disease while migrating and can expose domestic poultry to the virus while never showing signs themselves, according to the CDC.

The virus jumped to cattle herds for the first time ever earlier this year in a major escalation. Then, in October, a pig in Oregon tested positive for the virus, an especially concerning case as swine can host both bird and human flu viruses.

There has been no known human-to-human transmission yet. Still, the growing pattern of mammal-to-mammal transmission has infectious disease experts on guard against the possibility that H5N1 could eventually become a human pandemic.

"If it keeps spreading in animals, then it is eventually going to cause problems for humans, either because we don't have food because they've got to start exterminating flocks, or because it starts to make a jump in humans," Dr. Jerome Adams, a former surgeon general and the director of health equity at Purdue University, told Business Insider in April.

"The more it replicates, the more chances it has to mutate," he added.

The ongoing multi-state dairy cattle outbreak, which is believed to have started in Texas, has infected 865 herds across 16 states, according to the CDC, and has led to a growing number of human cases among US dairy and poultry workers.

The CDC has thus far confirmed 61 reported human cases and seven probable cases across the US, though some scientists estimate that the real number of infections is higher.

More than half of the human cases are tied to interaction with sick cattle. The remaining infections have been traced to exposure to sick poultry or have an unknown origin, the CDC said.

State of emergency

California's Wednesday announcement will give state and local authorities increased resources to study and contain the outbreak, Newsom said.

"This proclamation is a targeted action to ensure government agencies have the resources and flexibility they need to respond quickly to this outbreak," the governor said in a statement.

Earlier this month, the Agriculture Department said it would start testing the nation's milk supply for traces of the virus, requiring dairy farmers to provide raw milk samples upon request. Up until then, cattle testing for potential infections had been almost entirely voluntary.

Dr. Monica Gandhi, a professor of medicine and associate chief of the Division of HIV, Infectious Diseases, and Global Medicine at the University of California, San Francisco, said the declaration will likely give California a greater ability to surveil dairy farms for signs of the virus.

But declaring a state of emergency could be a double-edged sword.

Phrases "like 'state of emergency,' given that we've just been through a pandemic, can induce panic," Gandhi said.

And it's not time to panic yet, she said.

Gandhi praised the CDC's "very measured" messaging around the virus thus far and said health officials are closely monitoring the spread.

• Gov. Gavin Newsom of California declared a "proactive" state of emergency over the H5N1 bird flu.
• The virus has spread rapidly through US dairy cattle herds, with 16 states affected.
• The CDC reports low public risk with no human-to-human spread, but 61 human cases have been detected.

Gov. Gavin Newsom of California declared a state of emergency over the H5N1 avian influenza virus on Wednesday.

The bird flu has been spreading rapidly through US dairy cattle herds since March, with infections confirmed in 16 states. Its jump from birds to cows surprised many virologists and raised concerns about the possibility that it could mutate enough to sustain human-to-human transmission.

For now, the US Centers for Disease Control and Prevention has not detected humans spreading the virus to each other and says the risk to the public remains low.

Still, 61 human cases have been confirmed across the country, with 34 of them in California. Many of these cases have been linked to infected cows or birds.

Newsom's declaration, which his office called a "proactive action," followed the detection of new cattle infections on dairy farms in Southern California, according to the office's statement.

"This proclamation is a targeted action to ensure government agencies have the resources and flexibility they need to respond quickly to this outbreak," Newsom said in a statement.

The FDA has said that grocery-shelf beef and dairy continue to be safe to consume. However, the FDA and unaffiliated virus experts have advised against drinking raw milk, which is not pasteurized and can contain harmful microorganisms.

"While the risk to the public remains low, we will continue to take all necessary steps to prevent the spread of this virus," Newsom said.

Also on Wednesday, the CDC confirmed the first case of severe symptoms in a human H5N1 infection, in Louisiana.

Slowing bird flu's spread

The H5N1 virus was first detected in a California cow on August 30. Since then, the governor's office reported, the state has distributed millions of pieces of protective equipment to dairy-farm workers and run a public education campaign.

Infectious-disease experts have previously told BI that limiting the virus's spread through cows can help reduce the odds of sustained human transmission.

That's because the more the virus replicates itself, the more opportunities it has to mutate, and the more new mutations can take hold and spread to new animals. As H5N1 spreads in cattle, a mammal population that lives close to humans, it gets more chances to adapt to humans.

"There's such a vast amount of virus at the moment. And clearly it is changing, and it's doing new and unexpected things," Christopher Dye, an epidemiologist and senior research fellow at the University of Oxford, told BI in June.

In a paper in the medical journal BMJ, Dye and his colleague Wendy Barclay argued that the risk of a major human outbreak was "large, plausible, and imminent" — but not inevitable.

When that paper was published in early June, there had only been three confirmed human cases in the US.

"Influenza has always been a concern for decades and decades, and this particular form of influenza for at least two decades," Dye said. Bird flu, he added, has "risen to a level of concern, I think, which is greater than ever before."

• California's biggest raw milk brand tested positive for bird flu.
• With a voluntary recall underway, the company has started sending out milk to be pasteurized.
• Raw cheese, kefir, and butter are still being sold.

One of Robert F. Kennedy Jr.'s favorite raw milk producers is temporarily going pasteurized, as bird flu sweeps across California's dairyland.

Raw Farms is California's largest producer of raw milk products, and a huge name in West Coast wellness circles. This summer, the company partnered with carnivore diet influencer Paul Saladino and trendy LA grocery store Erewhon to produce a $19 raw kefir smoothie.

Now, the company is recalling all of its raw milk and raw cream on store shelves statewide, after initial retail tests of at least two batches of milk turned up positive for H5N1 bird flu.

In the meantime, raw milk produced at the Fresno-based dairy is being processed like regular milk.

"It's going from our dairies directly to a processing plant owned by somebody else to be pasteurized," Raw Farms founder Mark McAfee told Business Insider on Wednesday, adding that the move is a "horrible" one for his bottom line.

"We're getting about 20%" of normal sales revenue, he said.

Raw Farms isn't recalling its raw cheeses, butter, or kefir, and McAfee said that's because those products have been fermented, heated, cultured, or aged, and therefore are somewhat less of a concern to regulators.

Can you get bird flu from raw milk?

It's normal for raw milk to have viruses or bacteria floating around in it. Unlike pasteurized milk, raw milk is not heated to kill pathogens.

That's why the US Food and Drug Administration advises against anyone drinking raw milk. There's a risk of contracting stomach bugs like Salmonella or E. coli, which can cause food poisoning, and in rare cases hospitalization or death. Kids are especially at risk.

It's not clear whether people can actually get bird flu by drinking milk from a sick cow. So far, there have been no reports of raw milk drinkers catching bird flu, but there have been several cases of cats drinking raw milk from cows sick with bird flu, and then dropping dead afterwards.

"Like many foodborne illnesses, illnesses from raw milk are often underreported because many people aren't tested by a doctor in time to identify a pathogen and link the illness to a specific food," the Santa Clara County Public Health Department, the agency that first identified bird flu virus in Raw Farms products in November, told BI in a statement.

The FDA declined to comment for this story, citing an ongoing lawsuit against Raw Farms, which accuses the company of selling raw milk across state lines (that's forbidden under federal law).

A spokesperson for the agency pointed BI to a recent letter to dairy producers nationwide, which mentions that bird flu is a virus, like other viruses, that can't withstand pasteurization.

A bird flu outbreak will not stop the raw milk trend, McAfee says

McAfee is trying to set up some raw milk bottling and processing in another area of the state that isn't as affected by the current H5N1 outbreak as the Central Valley. He said he hopes to start selling raw milk again soon, after performing (and clearing) some additional tests.

"Hopefully, within the next 10 days, we'll have a dairy that's up and going, and products will be flowing from a different area of California," he said.

That would be welcome news to President-elect Trump's pick to head up Health and Human Services next year.

Kennedy has promised to end the FDA's "war" on raw milk. McAfee said he's been tapped by Kennedy's transition team to apply for a position advising the FDA on standards and policy for raw milk production.

"People don't really appreciate the deep science of this," he said. "I do."

He pointed to the latest science that suggests the biggest hazard for bird flu transmission lies not in the milk itself, but in dairy cow udders.

So far, of the 32 human bird flu cases reported in California, 31 have been traced back to cattle exposure.

The Centers for Disease Control and Prevention has been warning dairy workers to watch out for raw milk splashing into their eyeballs, and McAfee said his dairy workers wear eye protection.

• Two batches of raw milk from a trendy California brand have tested positive for bird flu this week.
• Bird flu has been spreading rapidly among cattle in the US.
• Experts say drinking raw milk is dangerous, and can cause food poisoning.

Another batch of raw milk just tested positive for bird flu in California.

Last Sunday, Fresno-based Raw Farm voluntarily recalled a first batch of cream top whole raw milk with a "best by" date of November 27. By Wednesday, the California Department of Public Health announced that a second batch of Raw Farm cream top, with a "best by" date of December 7 had also tested positive for bird flu, based on retail sampling.

"We're not making a big deal about it, because it's not a big deal," Kaleigh Stanziani, Raw Farm's vice president of marketing, said in a short video posted on YouTube after the farm's first voluntary recall was announced earlier this week.

She said there had only been an indication that there might be a "trace element of something possible," emphasizing that there had been no reported illnesses of Raw Farms cows or positive tests from the cattle.

Raw Farm owner Mark McAfee later told the LA Times that the California Department of Food and Agriculture had requested that his company "hold delivery of further products" until Friday, after conducting thorough testing of two Raw Farms and one creamery on Wednesday. (McAfee could not immediately be reached for comment by Business Insider during the Thanksgiving holiday.)

Raw milk may be helping bird flu spread — but not in the way you might think

Scientists suspect that cross-contamination of raw milk between animals may be one reason the H5N1 virus is spreading rapidly among cows in the US — and could even contribute to the human spread of the virus. The Centers for Disease Control and Prevention cautions that dairy workers might be able to contract bird flu by infected raw milk splashed into their eyes.

There is no definitive evidence yet that humans can get bird flu from drinking contaminated raw milk. Instead, health authorities generally recommend avoiding raw milk because of other serious health risks, including food poisoning with bacteria like Salmonella, E.coli, or Listeria.

There are no known health benefits of drinking raw milk. Instead, all evidence suggests that pasteurized milk is just as nutritious, and is safer to consume.

Still, raw milk has become a trendy product among some influencers. Gwenyth Paltrow says she has it in her coffee in the morning.

Robert F. Kennedy Jr., President-elect Trump's pick for Health and Human Services secretary, says he wants the US Food and Drug Administration to stop its "war" against raw milk.

Over the summer, "Carnivore MD" Paul Saladino released a raw milk smoothie in partnership with the elite Los Angeles health foods store Erewhon featuring unpasteurized (raw) kefir from Raw Farms, and powdered beef organs.

California has some of the loosest rules around raw milk in the country; it's generally fine for California retailers like health foods stores and grocers to sell it, raw milk products just can't be transported across state lines, per FDA rules.

Michael Payne, a researcher at the Western Institute of Food Safety and Security, told The Guardian that people consuming Dr. Paul's $19 smoothie were "playing Russian roulette with their health," and ignoring pasteurization, "the single most important food safety firewall in history."

California dairy farms have been seeing an uptick in bird flu cases since August. The state has reported 29 confirmed human cases of bird flu, and all but one of those was sourced back to cows.

Last week, the Centers for Disease Control and Prevention reported the first confirmed case of bird flu in a California child from Alameda County. The child had no known contact with infected farm animals, but may have been exposed to wild birds, the California health department said in a statement.

The child had mild symptoms and is recovering well after receiving antiviral drugs.