Portal, AZ - Rodeo, NM

Bird Flu Update

Updated By Dr. Howard Topoff and Dr. Eskild Petersen

What is bird flu?

Bird flu (avian influenza) is an infection from a type of influenza (flu) virus that usually spreads in birds and other animals. Rarely, humans can get bird flu from infected animals. Like the versions of flu that people usually get, bird flu can be mild or serious. It’s extremely rare for it to spread from person to person.

Here are two articles from The Washington Post that should answer MANY questions we receive from our community.

Bird Flu Detected In Raw Milk Sold At California Store

The H5N1 virus was found in a sample of unpasteurized milk at a store, prompting a recall of one batch. Health agencies have warned against the growing dietary fad.

 Bird flu, a virus that can also affect humans, has been discovered in a batch of raw milk sold in California store refrigerators, state regulators said Sunday. While there have been no reported illnesses in this most recent case, it comes just a few days after a child tested positive for bird flu for the first time in U.S. history.

A batch of whole raw milk from Raw Farm that has a “best by” date of Nov. 27, 2024, has been recalled after Santa Clara County health officials detected bird flu in a sample purchased for testing, the California Department of Public Health said in a news release. The farm is in Fresno County.

Retailers have been notified to pull the product from their refrigerator racks, the state health department said. Consumers who may have it in their homes are advised not to drink it.

Concerns over the H5N1 avian virus are mounting this year after scientists began detecting it in mammals such as dairy cows, indoor and outdoor cats, mice and a backyard pig. The H5 virus, formerly understood to circulate only among birds, has now also infected at least 55 people in the United States this year. However, the Centers for Disease Control and Prevention says that infection via an intermediary animal happens “very rarely.”

Unlike pasteurized milk — which undergoes a heating process that kills bacteria and viruses such as H5N1 — raw milk is associated with a number of serious health risks, including exposure to salmonella, E. coli, brucella, campylobacter and listeria.

“Public health experts have long warned consumers against consuming raw milk or raw milk products due to elevated risks of foodborne illness,” the California health agency said. “Drinking or accidentally inhaling raw milk containing bird flu virus may lead to illness. In addition, touching your eyes, nose, or mouth with unwashed hands after touching raw milk with bird flu virus may also lead to infection,” it added.

Pasteurization, named after 19th-century chemist Louis Pasteur, has been used routinely in milk production in the United States since the 1920s. By the 1950s, it had become a widespread practice that “led to dramatic reductions in the number of people getting sick,” the CDC said.

The practice is known to kill the H5N1 virus in milk. Yet dairy farmers say they’ve been seeing an increasing demand for unpasteurized milk, with social media influencers and raw dairy evangelists touting raw milk online to millions of viewers, often claiming unproven or largely disproven health benefits. Some states have taken steps to legalize its sale on store shelves. Robert F. Kennedy Jr. — who was recently tapped by President-elect Donald Trump to lead the Department of Health and Human Services — has said he wants to boost access to it.

The actress Gwyneth Paltrow, who has been criticized for touting unsupported health claims via her wellness brand Goop, said in a podcast interview that she drinks unpasteurized cream in her coffee daily, promoting the same brand of raw milk whose product is being pulled from California stores this week.

Though it’s possible to contract the virus through drinking raw milk, the majority of known human cases of H5N1 in the United States have been transmitted through close, prolonged and unprotected contact with infected birds — or places contaminated with their bodily fluids, according to the CDC. Humans can become infected when the virus is inhaled through dust or droplets in the air, or gets into a person’s eyes, nose or mouth.

As for symptoms, bird flu in humans has presented itself with a wide range of severity. Some have shown no sign of illness at all, the CDC said, while others have experienced severe symptoms or died of the disease. No deaths have been reported in the United States.

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Single Bird Flu Mutation Could Let It Latch Easily To Human Cells

The potential mutation would allow the virus to hitch itself to a protein on the surface of our cells, known as the receptor.

Scientists from the Scripps Research Institute are reporting that it would take just a single mutation in the version of bird flu that has swept through U.S. dairy herds to produce a virus adept at latching on to human cells, a much simpler step than previously imagined.

To date, there have been no documented cases of one human passing avian influenza to another, the Scripps scientists wrote in their paper, which was published Thursday in the journal Science. The mutation they identified would allow the virus to attach to our cells by hitching itself to a protein on their surface, known as the receptor.

William Schaffner, a professor of infectious diseases at Vanderbilt University Medical Center who did not participate in the study, called the research “sobering,” adding, “I had not known it would take just one mutation in the virus for it to attach itself to the receptors on human cells.”

However, he stressed that the H5N1 virus has been active for 20 years and “has multiplied billions upon billions upon billions of times and the spontaneous mutation that the authors describe,” has not been found, despite intense surveillance.

Yoshihiro Kawaoka, a professor of virology at the University of Wisconsin, who was not involved in the latest research but has studied bird flu extensively, said that statistically, the mutation probably already exists in H5N1-infected cows and humans, given that 1 in 10,000 infectious particles of the influenza virus is a mutant.

James C. Paulson, one of the paper’s authors, and several other top scientists agreed that it is statistically likely the mutation has occurred in the H5N1 virus but stressed that it has yet to be detected, and other barriers remain before the virus could be transmitted from one person to another. Paulson is a professor in the Department of Molecular Medicine at Scripps.

Since reaching North America in late 2021, H5N1 avian influenza has infected more than 700 dairy herds and sickened 58 people in the United States. Most of the people infected were farm workers whose jobs put them in frequent contact with cows or poultry. Most cases have been relatively mild, marked by symptoms such as the eye infection conjunctivitis. However, scientists and health officials have expressed concern about an infected teenager, who had been hospitalized for more than two weeks in British Columbia as of Nov. 26. (The Office of the Provincial Health Officer and BC Children’s Hospital both declined to say whether the teenager remains hospitalized.)

In past instances when humans have been infected with strains of bird flu, the mortality rate among those hospitalized has reached 30 percent or higher.

Because very few people have been infected with avian influenza, our immune systems have not adapted as they have to the seasonal flu. Public health officials worry about the possibility of a virulent strain of avian influenza getting loose in humans, one that could infect cells in the nose, throat and bronchial tubes.

Key factors have prevented this nightmare scenario. The virus has not shown the ability to spread from one person to another. Also, the virus that has infected cows and poultry prefers binding to the surface proteins, or receptors, of bird cells and is not well-suited to human cell receptors.

But all that can change if the virus mutates in the wrong way.

Mutations occur spontaneously as the virus replicates, but they can also occur if a virus infects a cell that is already infected by a different virus. If a person who already has seasonal flu is also infected with H5N1 from a cow or bird, the two viruses exchange genetic material, resulting in a new virus.

The Scripps team worked only with a key protein found on the surface of the virus, not the virus as a whole. They engineered specific mutations in the receptor binding protein found on the surface of H5N1 that had spread from a cow to a person.

What we need to do is to find out what additional mutations are needed for the bovine H5N1 viruses to become airborne transmissible in mammals,” Kawaoka said in his email. “But we cannot perform such experiments.”

Richard J. Webby, a virologist at St. Jude’s who was not involved in the study, called the findings “a little frightening.” He added, “I think most people probably would have assumed that it would take a couple of changes to make that switch.”

Not only does the virus have to bind to the human virus receptor, he said, “but you’ve also got to lose the ability to bind to the avian virus receptor, and that’s exactly what this one mutation did.”

Eric Stemmy, deputy chief at the respiratory diseases branch of the National Institute of Allergy and Infectious Diseases (NIAID), said the finding by the Scripps team “wasn’t really all that surprising.” The longer an avian virus circulates in mammals, the higher the risk it will develop mutations that better adapt it to mammalian hosts. 

Stemmy said the research underscores the need for strong surveillance and pandemic preparedness. The United States already has a stockpile of vaccine doses that target H5N1. By the end of the first quarter of 2025, there will be up to 10 million doses, “based on a candidate vaccine virus that remains well-matched to the virus circulating in dairy cattle,” according to a spokesperson for the government’s Administration for Strategic Preparedness and Response.

Paulson said there are still important gaps in what is known about the H5N1 virus that has been found in cows, birds and a small number of humans.

“We may be missing some things frankly,” he said. “Why isn’t the virus causing respiratory disease. That is astonishing to me because, in the past, H5N1 virus caused severe illness.”