Bird flu may need a single mutation to spread among humans, study finds

A photo of cows being milked at the Raw Farm in Fresno, California.

Cows are milked at a Fresno dairy farm. More than 400 California dairy farms have been confirmed to have suffered outbreaks of H5N1 bird flu virus.
(Tomas Ovalle / For The Times)

Good morning, and welcome to the Essential California newsletter. I hope you’re enjoying your Saturday. I know my husband is — he’s currently putting holiday outfits on our two dogs, Princess Leia and Sassy. Here’s what you need to know to start your weekend:

Newsletter

You’re reading the Essential California newsletter

Our reporters guide you through the most important news, features and recommendations of the day.

You may occasionally receive promotional content from the Los Angeles Times.

The H5N1 bird flu virus may need just one mutation to be a threat to humans, a study found. Here’s what you need to know.

“Yikes,” “Oh great” and “You’ve got to be kidding me” were all reactions I got from friends when I texted them this news: The bird flu may only need one mutation in order to spread among humans, according to a study published this week in the journal Science.

The mutation “could open the door to widespread human infections and possibly even a pandemic,” experts told my colleague Susanne Rust. But there is a caveat — it’s unclear if this mutation will occur.

Here’s a look at what the study says, what it doesn’t say and why scientists are nervous about the growing number of dairy and poultry herds in California that have been infected with the virus.

A photo of cows leaving a dairy barn after milking.

The spread of the H5N1 bird flu virus among dairy cows has worried health experts, who say it increases the risk of the virus becoming a greater threat to humans.
(Tomas Ovalle/For The Times)

Bird flu needs the right ‘key’ for human-to-human transmission

Scientists at the Scripps Research Institute wanted to know what it would take for the current strain of H5N1 bird flu to become a human pandemic, my colleague Susanna reports.

In order for the virus to latch onto the cells of its host and begin replicating, it needs the right spike or “key” to get in.

You might be thinking, “But haven’t people already been infected with the bird flu?” Yes, there have been more than 50 known cases in humans in the U.S.

But many of them involved dairy workers who were likely sprayed in the eyes and nose with infected milk from cows, Susanna reports. This type of repeated exposure allowed the virus to kick down a door rather than open it with the right key, researchers say.

The scientists at Scripps began looking at how H5N1 could gain a key to target human cells. They found a single mutation of the hemagglutinin protein — the “H” in H5N1 — would allow the virus to spread among humans.

Don’t stock up on face masks, toilet paper and flour just yet

The study shows what it would take for H5N1 to become a threat to humans, but it doesn’t say when — or even if — this mutation will happen.

“Although the researchers demonstrated that it was possible for the virus to become a threat to humans with just one genetic change, that does not mean nature will follow that specific path,” my colleague Susanna reports.

Several unpredictable factors can determine the trajectory of a virus, and that may be why H5N1 hasn’t been able to widely infect humans so far.

A photo of Jersey cows looking up from feeding at Mark McAfee's Raw Milk dairy.

Jersey cows look up from feeding at Mark McAfee’s Raw Milk dairy.
(Tomas Ovalle/For The Times)

But H5N1 still has opportunities to evolve at dairy and poultry farms, scientists say

The increasing number of outbreaks at farms provides the virus with the right conditions to develop a mutation, scientists warn.

This week, all raw milk and cream from Fresno-based Raw Milk dairy farm were recalled from store shelves. The move came after public health officials found H5N1 in raw milk samples last month.

More than 700 dairy herds in 15 states have been infected with the virus, according to data from the Centers for Disease Control and Prevention posted on Thursday. And the virus has been reported at 23 commercial poultry farms in California in the last 30 days — affecting more than 5.6 million birds.

Amid the rising number of cases in the state, the lab charged with tracking and preventing the spread of bird flu has been roiled by workplace tensions, L.A. Times labor reporter Suhauna Hussain found.

Current and former employees say many workers have left the California Animal Health and Food Safety Laboratory due to poor management. That exodus has resulted in a skeletal crew at the lab that is overworked and burned out.

As the number of cases continues to grow, the U.S. Department of Agriculture on Friday ordered testing of the nation’s milk supply for H5N1 and laid out a staged testing strategy that will allow the federal agency to track and monitor the virus.

The week’s biggest stories

Hunter Biden, dressed in a suit, walks toward a federal court building in Los Angeles.

Hunter Biden, right, and his wife, Melissa Cohen Biden, arrive in federal court for his trial on felony tax charges in September in Los Angeles.
(Jae C. Hong / Associated Press)

The federal judge in Hunter Biden’s tax case denounced the president’s pardon

A Northern California community is “devastated” after a school shooting left two boys injured

  • Authorities say a 56-year-old man staged an attack Wednesday on a Christian elementary school that ended with the attacker dead.
  • The Butte County sheriff described the gunman as a homeless, mentally ill man with a long criminal record who targeted the school due to its affiliation with the Seventh-day Adventist Church.

This week’s 7-magnitude earthquake in Northern California highlighted the potential danger of tsunamis

  • A rare tsunami warning was issued and later canceled across the region, a reminder to prepare and know how to respond in case of such emergencies.
  • The offshore earthquake and short-lived tsunami warning left some Northern California residents feeling “emergency whiplash.”

“Missing women” cases in Los Angeles go viral online, even as the facts get complicated

  • In the same week, Chanel Banks and Hannah Kobayashi were reported missing. Banks was found in Texas, while authorities say Kobayashi is “voluntarily missing.”
  • Officials with the Los Angeles Police Department said Kobayashi was seen crossing the border into Mexico. Here is a review of what we know about her case.

More big stories


Get unlimited access to the Los Angeles Times. Subscribe here.


This week’s must reads

An 18-year-old man wearing a white hoodie stands in front of a tree.

(Melissa Sue Gerrits / For The Times)

L.A. County left a baby in the care of her 11-year-old brother. Now, she’s dead. The baby’s mother left her children home alone for days without enough food, according to her son and calls to a child protective services hotline from school counselors.

But DCFS never opened a case.

More must reads


How can we make this newsletter more useful? Send comments to [email protected].


For your weekend

Collage of food photos from the 2024 101 list

Here are the 101 best restaurants in Los Angeles, according to Times restaurant critic Bill Addison and columnist Jenn Harris.

Going out

Staying in

How well did you follow the news this week? Take our quiz.

A collection of photos from this week's news quiz.

(Times staff and wire photos)

For what reason did Gov. Newsom call the special session of the state Legislature that started Monday? Plus nine other questions from our weekly news quiz.

Have a great weekend, from the Essential California team

Hunter Clauss, multiplatform editor

Check our top stories, topics and the latest articles on latimes.com.

Related Posts


This will close in 0 seconds