Why has California declared a state of emergency over bird flu?

California Governor Gavin Newsom declared a state of emergency on Wednesday in response to growing concerns about bird flu cases in the state. Meanwhile, on the same day, the country’s first severe case of the virus was reported in Louisiana.

Here is what we know so far about the virus and why it has become so serious.

Why has California declared a bird flu emergency?

The emergency declaration on Wednesday was made after several more dairy cows tested positive for the virus in southern California.

Newsom said declaring a state of emergency would make funds available to “streamline and expedite” efforts to tackle an outbreak.

Since bird flu was detected in dairy farms in the United States in 2022, it has spread to hundreds of herds of cattle in 16 US states and caused infections in some dairy farm workers – all of which have been mild so far.

However, on Wednesday, the first severe illness from the H5N1 strain of the virus in a human was reported in Louisiana.

The 65-year-old, who is understood to have underlying health conditions, has been hospitalised and is in critical condition, according to the Centers for Disease Control and Prevention (CDC).

“CDC confirms first severe case of H5N1 Bird Flu in the US. While an investigation into the source of the infection is ongoing, it has been determined that the patient had exposure to sick and dead birds in back yard flocks,” the agency said.

The H5N1 strain was first detected in the US in March this year. Since then, 61 people in seven states have been reported to have contracted the virus. Most of them have suffered only mild symptoms, and 34 of them are in California.

While the detection of bird flu in humans has historically been rare, more and more humans are testing positive for the virus in recent years, especially in North America.

Before 2022, human cases of bird flu had not been reported in the US at all. In 2022, only one human case of bird flu had been detected in the US and no human cases were detected in 2023.

On November 9, Canada reported its first human case of H5N1 in a teenager in the British Columbia province.

Attendees view cows that are shown by exhibitors at the state fair in West Allis, Wisconsin, US, on August 9, 2024. Dairy farmers said they were taking precautions by testing for avian flu while exhibiting cattle during the fair [Jim Vondruska/Reuters]

What is bird flu?

Bird flu, or avian influenza, is a virus that typically spreads among birds but can also affect humans and other animals, including dairy cows, seals, cats, dogs, foxes, skunks, tigers, leopards and farmed mink, according to the CDC. So far, there have been no cases of bird flu passing from one human to another.

Bird flu has killed millions of birds worldwide and different strains have been detected in different regions.

It can be extremely dangerous for humans. Since the virus was first detected nearly three decades ago in China, about 860 people have become infected in 23 countries, including China, Egypt, Vietnam and Turkiye, according to the World Health Organization (WHO). Of those, 463 people died from the virus, giving a huge 52 percent death rate.

The virus became a global concern in 1996 when the H5N1 strain was first detected among domestic waterfowl in southern China.

That was the first time the virus was detected in humans as well. In Hong Kong, 18 people were reported to be infected, of whom six people died.

Between 2003 and 2005, the H5N1 strain re-emerged in China and spread to poultry in Africa, Europe and the Middle East.

Between 2014 and 2016, other strains including H5N6 and H5N8 emerged in birds in several parts of the world, including the US. H7N3 was detected in turkey farms in the US in March 2020. Between 2020 and 2022, these variants have spread among birds and cattle globally.

Between 2021 and 2023, the H5N1 virus has spread among birds in the US and Canada. During this time, other strains have also been detected in the US.

How is H5N1 different from other strains of bird flu?

H5N1 is considered the most “pathogenic” of the bird flu strains, meaning it is more deadly, with a death rate of approximately 60 percent for humans.

Some other strains, such as the H7N9 strain, can also infect humans, but tend to be milder. H7N9 has a death rate of 20 percent, according to the National Institutes of Health (NIH). That strain has been detected in China, Malaysia, Canada and Hong Kong in the past. The cases detected in Malaysia and Canada were in people who had travelled to those countries from China.

According to research published by the NIH in 2006, the H5N1 virus is more deadly because it causes “massive inflammation” and affects the immune system.

Both of these factors can lead to complications such as pneumonia or multi-organ failure, which are typical causes of death from H5N1.

What are the symptoms of bird flu?

In humans, the symptoms of the virus, including the H5N1 strain, include:

• Redness in the eyes, or conjunctivitis.
• Fever.
• Cough and sore throat.
• Runny or stuffy nose.
• Muscle aches
• Headaches
• Fatigue
• Shortness of breath

How does bird flu spread to humans?

Humans can catch bird flu if the virus enters their system through their eyes, nose or mouth.

This happens when the virus circulates in the air in dust or in droplets, which are inhaled by humans. The virus can get into the air and ground when infected birds “shed” it through their saliva, mucous and faeces, according to the CDC.

The CDC also reports that there is no evidence that the virus spreads from humans to other humans.

Can you get bird flu from eating chicken?

The CDC advises against eating uncooked or improperly cooked poultry.

It says there is no evidence that people in the US have been infected with bird flu after eating properly cooked chicken or poultry, but there have been suspected cases in Southeast Asia of people contracting the virus after eating uncooked poultry and consuming poultry products such as blood.

How can you avoid contracting bird flu?

By avoiding contact with animals and birds that are infected or suspected of being infected with bird flu.

The CDC advises staying away from sick or dead wild birds and poultry, and wearing personal protective equipment (PPE) if coming in contact with them is unavoidable. A bird that does not appear to be sick could still have the virus, the CDC warns.

In the UK, the National Health Service (NHS) also advises the following: “Markets where live birds are sold can also be a source of bird flu. Avoid visiting these markets if you’re travelling to countries that have had an outbreak of bird flu.”

The CDC advises against consuming raw milk or raw milk products – ie, those which have not been pasteurised (a heating process which kills germs) – especially from animals with confirmed or suspected bird flu. Raw eggs should also be avoided.

Is there a vaccine?

There is no bird flu vaccine authorised for humans. However, vaccines for birds and poultry are available and are used to contain the spread of the disease.

The seasonal influenza vaccine available in some countries does not provide protection against bird flu.

The CDC has reported that work is ongoing to produce a human vaccine for bird flu.

In July this year, the US government provided funding of $176m to Moderna, one of the manufacturers of the COVID vaccine, to develop a flu vaccine which would be effective against bird flu.