Zoonotic Bird Flu News since 24 Jan till 6 Feb 2023

'Major Leap' in Bird Virus Threatens Yet Another Pandemic [The Daily Beast, 6 Feb 2023]

By David Axe

The same highly pathogenic bird-flu virus that’s killed tens of millions of chickens and other birds over the past year just got a lot closer to infecting people, too.

An unusual outbreak of the H5N1 virus in minks—relatives of weasels—at a Spanish fur farm last fall also exposed the farm’s staff to the virus. Swift action by health authorities helped prevent any human infections. This time.

But bird flu isn’t going away. And as H5N1 continues to circulate in domestic and wild birds, causing millions of animal deaths and tightening the supply of eggs, it’s also getting closer and closer to the human population. “This… avian influenza has the potential to become a major problem to humans,” Adel Talaat, a professor of pathobiological sciences at the University of Wisconsin-Madison, told The Daily Beast.

It might be a matter of time before H5N1 achieves large-scale “zoonosis” and makes the leap to the human species. If and when that happens, we could have yet another major viral crisis on our hands. On top of the COVID pandemic, worsening seasonal RSV, the occasional monkeypox flare-up and annual flu outbreaks.

Reports this week suggested that the current wave of bird flu could be crossing over into mammals with more regularity. Scientists found traces of bird flu in seals that died in a “mass mortality event” in the Caspian Sea in December, and the BBC reported this week that tests in Britain had found the virus in a range of mammals up and down the country. On Jan. 9, the World Health Organization was informed that a 9-year-old girl in Ecuador had tested positive.
Bird flu isn’t new. Scientists first identified the virus back in the 1870s. There’ve been dozens of major outbreaks over the years—and they’ve grown more frequent, and more severe, as the global population of domestic poultry has expanded in order to feed a growing human population.

H5N1, a more-severe “highly pathogenic avian influenza” virus—or HPAI—first appeared in China in the 1990s. It and other HPAIs have achieved zoonosis on a small scale, mostly in Asia. Several dozen people have died of bird flu in recent decades.

But so far, bird flu has mostly infected, well, birds. That makes it a huge problem for poultry farmers. And for people who buy eggs, of course. The current H5N1 outbreak has killed, or compelled farmers to cull, nearly 60 million chickens, turkeys, geese and ducks in the United States alone. The cullings drove up the price of eggs to nearly $5 per dozen at U.S. grocery stores last fall, according to the U.S. Department of Agriculture. That’s several times the long-term average price.

“The ability to achieve sustained transmission in a mammal is a major leap for flu viruses, so the mink event is a big deal.”
— James Lawler, University of Nebraska Medical Center

Bird Flu Taking the Leap
Higher egg prices will be the least of our problems if large-scale zoonosis ever triggers a human bird-flu pandemic. And that’s why scientists and health officials keep a close eye on H5N1 and related HPAIs as they spread and mutate. For epidemiologists, the bird-flu outbreak at the mink farm in northwestern Spain was a giant red flag. An ominous sign that major zoonosis might be getting more likely.

Spanish health officials first noticed the outbreak in early October, when the death rate among minks at a large farm in Galicia tripled. Biological samples from the farm’s 52,000 minks contained H5N1. It was the first time bird flu had infected farmed minks in Europe.

Authorities ordered the culling of all the minks at the affected farm. At the same time, they quarantined and tested the farm’s 11 workers. Luckily, none had caught the virus.

It was a close call. And all the more worrying because no one knows for sure what happened.

“The source of the outbreak remains unknown,” a team led by virologist Montserrat Agüero reported in the latest issue of Eurosurveillance, an epidemiology journal. It’s possible wild birds spread the virus to the minks. It’s also possible the pathogen was present in the minks’ food, which contains raw chicken.

Equally troubling, the virus didn’t just spread from birds to minks. It may also have spread from minks to other minks, as well, Agüero’s team discovered. “This is suggested by the increasing number of infected animals identified after the confirmation of the disease.”

That post-zoonosis transmission within a new species is how an animal virus such as H5N1 could cause a new pandemic. It’s what happened with COVID, after the SARS-CoV-2 virus spread from bats or pangolins to people back in late 2019. It’s what happened with monkeypox, after that pathogen first leaped from monkeys and rodents to human beings, possibly decades ago.

Alarming Spread of Bird Flu Continues as More Species Infected [ScienceAlert, 6 Feb 2023]

Experts have warned that the recent detection of bird flu in mammals including foxes, otters, minks, seals, and even grizzly bears is concerning but emphasized that the virus would have to significantly mutate to spread between humans.

Since late 2021, Europe has been gripped by its worst-ever outbreak of bird flu, with North and South America also experiencing severe outbreaks.

This has led to the culling of tens of millions of domestic poultry worldwide, many with the H5N1 strain. The global outbreak is also responsible for the deaths of tens of thousands of wild birds.

Tom Peacock, a virologist at the Imperial College London, told AFP that it constitutes a "panzootic" – a pandemic among animals, in this case birds.

"We are not fully sure why it's happening now but we think this might be driven by a slightly different strain of H5N1 which is spreading very effectively in wild, migratory birds," Peacock said.

It is rare that bird flu jumps over into mammals – and rarer still that humans catch the potentially deadly virus.

On Thursday, the UK Health Security Agency said that a fox had recently tested positive for H5N1.

It joins eight foxes and otters which tested positive in the UK last year, all of which had a PB2 mutation.

Peacock said that this mutation "allows the virus to replicate better in mammalian cells".

But further mutations would be "required for the virus to cause a flu pandemic" in humans, he added.

France announced last week that a cat had been put down after testing positive for H5N1.
And last month, the US state of Montana's parks service said three grizzly bears with bird flu had been euthanized.

All of these mammals were suspected to have eaten infected birds.

Paul Wigley, a professor of animal microbial ecosystems at the UK's Bristol University, said that while "there is no transmission within mammalian populations, the risk to humans remains low".

Potential to cause pandemic?
However two recent larger scale infections have raised concerns that bird flu has the potential to spread between mammals.

One was an outbreak of H5N1 with the PB2 mutation at a Spanish farm in October that led to the culling of more than 50,000 minks.

Research published in the journal Eurosurveillance last month said its findings "indicate that an onward transmission of the virus to other minks may have taken place in the affected farm".

Transmission between the minks has not been confirmed, with further research ongoing.

The mass death of some 2,500 endangered seals found along Russia's Caspian Sea coast last month has also raised concern.

A researcher at Russia's Dagestan State University, Alimurad Gadzhiyev, said last week that early samples from the seals "tested positive for bird flu", adding that they were still studying whether the virus caused the die-off.

Peacock warned there have been mixed reports from Russia about the seals, which could have contracted the virus by eating infected seabirds.

But if the seals did give bird flu to each other it "would be yet another very concerning development", he added.

"The mink outbreaks, the increased number of infections of scavenger mammals and the potential seal outbreak would all point to this virus having the potential to cause a pandemic" in humans, he said.

Mixing point
David Heymann, an infectious disease specialist at the London School of Hygiene and Tropical Medicine, urged caution.

More bird flu cases could be being detected in mammals because countries have ramped up testing, he said.

"This may have been going on for years and nothing has really occurred," he told AFP.

But it was always concerning when a flu virus enters mammals "because they're often the mixing point of influenza viruses, or they create an environment where mutations can occur and then can become adapted in humans", he added.

Even if that did occur, he said there were excellent surveillance systems in Europe and North America, and that H5N1 has been heavily researched since it first emerged in China and Hong Kong in 1996.

If H5N1 did mutate into a strain that could circulate among humans, the current seasonal flu vaccine could be fairly easily updated to include it, he said.

The UK Health Security Agency said "there is no evidence of sustained human to human transmission" of bird flu.

Over the last two decades, there have been 868 confirmed H5N1 cases in humans with 457 deaths, according to the World Health Organization. There were four confirmed cases and one death last year.

Last month, Ecuador reported South America's first case of the A(H5) bird flu virus in a human – a nine-year-old girl who was in contact with backyard poultry.

The experts called for continued surveillance of avian influenza in wild birds, poultry and mammals, in order for humans to limit their exposure.

An Even Deadlier Pandemic Could Soon Be Here [The New York Times, 3 Feb 2023]

By ZEYNEP TUFEKCI

Opinion | H5N1 Bird Flu is Causing Alarm. Here’s Why We Must Act.
As the world is just beginning to recover from the devastation of Covid-19, it is facing the possibility of a pandemic of a far more deadly pathogen.

Bird flu — known more formally as avian influenza — has long hovered on the horizons of scientists’ fears. This pathogen, especially the H5N1 strain, hasn’t often infected humans, but when it has, 56 percent of those known to have contracted it have died. Its inability to spread easily, if at all, from one person to another has kept it from causing a pandemic.

But things are changing. The virus, which has long caused outbreaks among poultry, is infecting more and more migratory birds, allowing it to spread more widely, even to various mammals, raising the risk that a new variant could spread to and among people.

Alarmingly, it was recently reported that a mutant H5N1 strain was not only infecting minks at a fur farm in Spain but also most likely spreading among them, unprecedented among mammals. Even worse, the mink’s upper respiratory tract is exceptionally well suited to act as a conduit to humans, Thomas Peacock, a virologist who has studied avian influenza, told me.

The world needs to act now, before H5N1 has any chance of becoming a devastating pandemic.

We have many of the tools that are needed, including vaccines. What’s missing is a sense of urgency and immediate action.

The best defense against a new deadly pathogen is aggressively suppressing early outbreaks, which first requires detecting them quickly. The United States, the World Health Organization and global health officials already have influenza surveillance networks, but many avian influenza experts told me they don’t think the networks are functioning well enough given the threat level. Such surveillance would need to prioritize people in the poultry industry but also expand beyond that.

Thijs Kuiken, an expert in avian influenza at Erasmus University Medical Center in Rotterdam, the Netherlands, says farms for pigs — another species susceptible to influenza — should also be surveilled for bird flu. People interacting with wild birds and animals, as well as susceptible species of pets like ferrets, are also at higher risk. It’s not enough to detect, though: Suppression would require a major effort and global coordination.

Unfortunately, mink farms must be shut down — even if it means killing the minks. They are typically killed anyway for their fur at about 6 months of age. It’s hard to imagine a better way to incubate and spread a deadly virus than letting it evolve among tens of thousands of animals with an upper respiratory tract similar to ours crowded together. When the coronavirus infected Danish mink farms in 2020 and the minks generated new variants that then infected humans, the efforts to save the industry were futile because the outbreaks were uncontrollable.

If different strains of flu have infected the same person simultaneously, the strains can swap gene segments and give rise to new, more transmissible ones. If a mink farmworker with the flu also gets infected by H5N1, that may be all it takes to ignite a pandemic.

To avoid this, quick testing should be widely available and easy to obtain globally, especially for poultry workers and people handling wild birds or other wildlife. And current testing capabilities should be quickly expanded. There are 91 public health labs in the United States that can test for H5 influenza. Positive results are sent to the Centers for Disease Control and Prevention, where further analyses can detect H5N1 within about 48 hours. But plans should be in place to increase the amount of tests and testing facilities in case demand ramps up.
Perhaps the best news is that we have several H5N1 vaccines already approved by the Food and Drug Administration whose safety and immune response have been studied.

The U.S. government has a small H5N1 vaccine stockpile, but it would be nowhere near enough if a serious outbreak occurred. The current plan is to mass-produce them if and when such an outbreak occurs, based on the particular variant involved.

There are several problems, though, with this approach even under the best-case scenarios. Producing hundreds of millions of doses of a new vaccine could take six months or more.

Worryingly, all but one of the approved vaccines are produced by incubating each dose in an egg. The U.S. government keeps hundreds of thousands of chickens in secret farms with bodyguards. (It’s true!) But the bodyguards are presumably there to fend off terror attacks, not a virus. Relying on chickens to produce vaccines against a virus that has a 90 percent to 100 percent fatality rate among poultry has the makings of the most unfunny which-came-first, the-chicken-or-the-egg riddle.

The only company with an F.D.A.-approved non-egg-based H5N1 vaccine expects to be able to produce 150 million doses within six months of the declaration of a pandemic. But there are seven billion people in the world.

The mRNA-based platforms used to make two of the Covid vaccines also don’t depend on eggs. Scott Hensley, an influenza expert at the University of Pennsylvania, told me that those vaccines can be mass-produced faster, in as little as three months. There are currently no approved mRNA vaccines for influenza, but efforts to make one should be expedited.

If the W.H.O. is to take the lead in expanding global vaccine manufacturing, it needs the support of wealthy countries and the cooperation of large pharmaceutical companies that have the patents and know-how.

A big challenge to stockpiling flu vaccines is that they can lose potency over time and need updating as new variants arise. The U.S. government is skeptical about creating a large stockpile, fearing that stored vaccines may not be effective against whatever strain became pandemic, and worries that stockpiles will expire anyway. Officials also have faith that they can get new flu vaccines mass-produced rapidly.

Many influenza experts told me that older vaccines could still provide some protection against severe outcomes or death. Peter Palese, a professor of microbiology at the Icahn School of Medicine at Mount Sinai, who established the first genetic maps for influenza A, B and C viruses, told me that such stockpiles would be especially useful for essential workers.

In 2017, the C.D.C. found that the H5N1 vaccine made in 2004 and 2005 helped protect ferrets against an H5N2 virus in 2014. Investigations in 2006 showed that 80 percent of the U.S. stockpile of earlier H5N1 vaccines were still potent a full year after their expected one-year shelf life had passed. In 2019, another study found that H5N1 vaccines produced as early as 2004 were still potent a full 12 years later.

We could also allow voluntary vaccination, especially for high-risk groups like poultry workers and health care workers, who would be treating patients should outbreaks occur. Voluntary vaccination could also produce larger-scale data on the safety and dosing specifics of vaccines. Vaccinating poultry workers has the additional big benefit of helping suppress outbreaks in the first place.

Several influenza experts I spoke to bemoaned the lack of more widespread vaccination for chickens and turkeys. Had all poultry been vaccinated earlier, perhaps H5N1 would have never spread so widely to wild birds. It’s late, but mass vaccination of poultry and pigs should begin quickly.

Even getting more people vaccinated — especially poultry and pig farmworkers — against the regular influenza can help. With less regular flu in the world, there would be fewer hosts for an H5N1 virus to co-infect, a process that can lead to strains of H5N1 that can spread more easily.

We already have antivirals for influenza, which work regardless of strain, but they need to be administered early, which requires widespread early testing, easy access, and sufficient and equitable stockpiles globally.

Scientists are working toward a universal flu vaccine, potentially covering all variants as well as future pandemic ones — a moonshot, perhaps, but worth the investment.

The pace of developments has been disquieting. Until 2020, when the new H5N1 strain began to spread extensively among wild birds, most big outbreaks occurred among poultry. But now, with wild birds acting as conduits, it’s not just the biggest outbreak ever among poultry, causing the death of at least 150 million animals so far, but it is also steadily expanding its reach, including to mammal species like dolphins and bears.

In 2006, when scientists discovered that H5N1 had not spread easily among humans because it settles deep in their lungs, Kuiken of Erasmus University Medical Center warned that if the virus evolved to bind to receptors in the upper respiratory tract — from which it could become more easily airborne — the risk of a pandemic among humans would rise substantially. The mink outbreak in Spain is a signal that we might be moving along exactly that path.

It’s hard to imagine clearer and more alarming warning signs of a potentially horrific pandemic.
The public, of course, doesn’t want to hear about another virus, and Congress isn’t even willing to keep funding efforts against the current one.

We could get lucky — we’ve had bird flu outbreaks before without human spread. But it seems foolish to count on that. A pandemic strain may have a much lower fatality rate than the 56 percent of known human cases so far, but it still could be much more deadly than the coronavirus, which is estimated to have killed 1 percent to 2 percent of those infected before vaccines or treatments were available. Deadly influenza pandemics occur regularly in human history, and they don’t wait until people recover from an earlier outbreak, no matter how weary we may all feel.

This time, we have not just the warning, but also many of the tools we need to fend a pandemic off. We should not wait until it’s too late.

Bird flu outbreak is spilling over into mammals. What does that mean for humans? [USA Today, 3 Feb 2023]

By Adrianna Rodriguez

One of the world’s largest outbreaks of bird flu, which led to the slaughter of millions of chickens to limit its spread, appears to be spilling over into mammals.

The U.S. Department of Agriculture said the avian influenza A virus has been detected in mammals such as skunks, bears, a raccoon and a red fox.

Though most cases were detected in Oregon, positive tests in mammals were confirmed in the following states, according to the USDA's Animal and Plant Health Inspection Services:
• Alaska
• Colorado
• Idaho
• Illinois
• Montana
• Nebraska
• New York
• Washington

Meanwhile in the United Kingdom, the Animal and Plant Health Agency found positive cases in otters and foxes. The agency also said a cat tested positive in France, and the highly contagious pathogen caused a large outbreak in a Spanish mink farm.

How is the bird flu being transmitted?
Most of these infections are probably independent cases in which a mammal eats an infected bird, said Jürgen Richt, professor and director of the Center on Emerging and Zoonotic Infectious Diseases at Kansas State University.

It may be happening more often during this outbreak as viral transmission increases among wild birds, such as ducks, geese and swans.

The outbreak at the Spanish mink farm could be a special case in which the virus transmitted from mammal to mammal, Richt said.

What does this mean for humans?
Though more research is needed, it doesn't bode well for humans.

"If this virus has mammalian adaption and can transmit between mammals, humans are immunologically naive … and humans are mammals," Richt said.

The U.S. Centers for Disease Control and Prevention said the “bird flu situation remains primarily an animal health issue.” Only four human infections have ever been reported in the U.S., the CDC said.

Bird flu is not a foodborne illness, so poultry and eggs found in grocery stores are safe to eat, Gregory Martin, a poultry educator at Penn State Extension, told USA TODAY last month.
Symptoms of bird flu in humans

The bird flu virus can cause mild to severe symptoms, including:
• Eye redness
• Fever
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle or body aches
• Headaches
• Fatigue
• Shortness of breath

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

Avian Flu Jumps to Mammals: Could Humans be Next? - HS Today [HSToday, 2 Feb 2023]

By Kylie Bielby

According to the World Health Organization (WHO), zoonotic influenza infections in humans may be asymptomatic or may cause disease, from conjunctivitis or mild, flu-like symptoms to severe, acute respiratory disease or even death.

While public health officials say the risk to humans is still very low, they are concerned about mutations after a number of mammals have been found to have contracted the bird flu virus.

According to the World Health Organization (WHO), zoonotic influenza infections in humans may be asymptomatic or may cause disease, from conjunctivitis or mild, flu-like symptoms to severe, acute respiratory disease or even death, depending on factors related to the virus causing infection and the infected host. Rarely, gastrointestinal or neurological symptoms have been reported. WHO assesses the risk to the human population to be low, however recent studies show that the virus has shown potential mutation among cases in mammals.

In the U.K., the Animal and Plant Health Agency (APHA) has tested 20 mammals, and found eight were positive for highly pathogenic avian influenza (HPAI) H5N1. It is likely that these mammals fed on very sick or dead birds but there is also concern that the virus is spreading between mammals following additional data from around the world.

APHA says that four of the eight positive cases have genome sequences available and all show the presence of a mutation which is associated with potential advantages for mammalian infection. Together with supporting international data, the results are suggestive of sporadic mammalian spillover events. Last year for example, infections were found in about a dozen species in the United States, including raccoons, foxes, seals and grizzly bears. An outbreak of avian influenza on a mink farm in Spain provides the strongest evidence so far that the H5N1 strain of flu can spread from one infected mammal to another, and Hualan Chen, a virologist at the Harbin Veterinary Research Institute in China said the spread of the virus between mammals imposes a higher risk to public health.

APHA is working with the UK Health Security Agency (UKHSA) and the Department for Environment, Food and Rural Affairs to investigate the risk to human health of avian influenza in England. A recent UKHSA report noted that from October 1, 2022 to December 15, 2022, health protection systems recorded 2,085 human exposure episodes (where a person was directly exposed to an infected bird). There is likely to be substantial under ascertainment.

Based on the 29% of incidents for which there is data, personal protective equipment was used in 27.3% of exposures, and antiviral prophylaxis in 15.9% of exposures. Symptoms were reported following 31 (4.3%) exposures, with 24 symptomatic swabs being carried out (77.4% of those eligible).

Last year, a man in Colorado was diagnosed with avian influenza. Media reports at the time indicated he was involved with culling poultry and infected by a sick bird. According to the Centers for Disease Control and Prevention (CDC), he had mild symptoms, was isolated, and recovered. Nichola Hill, an assistant professor of biology at the University of Massachusetts said the fact that his symptoms were mild is concerning because it makes the virus harder to detect and track, as infected individuals may ignore mild symptoms and not seek treatment—much like COVID-19.

And last month, WHO was notified of a human infection caused by an avian influenza virus. The case, a nine-year-old girl, living in a rural area in the province of Bolívar, Ecuador, was in contact with backyard poultry, which was acquired a week before the onset of her symptoms.

As of January 18, WHO reported that she remained hospitalized, in isolation, and treated with antivirals.

CDC says that human infections with bird flu viruses have occurred most often after unprotected contact with infected birds or surfaces contaminated with bird flu viruses.

However, it notes that some infections have been identified where direct contact with infected birds or their environment was not known to have occurred.

“The spread of bird flu viruses from one infected person to a close contact is very rare and when it has happened, it has only spread to a few people,” CDC says. “However, because of the possibility that bird flu viruses could change and gain the ability to spread easily between people, monitoring for human infection and person-to-person spread is extremely important for public health.”

Currently there are no approved vaccines for preventing avian influenza in humans. However, candidate vaccines have been developed for pandemic preparedness purposes.

Jonathan Runstadler, professor and chair of the Department of Infectious Disease & Global Health at Cummings School of Veterinary Medicine, believes this particular outbreak will not be going away any time soon. It differs from earlier outbreaks in that this time around the whole H5N1 virus, not just a part of it, is circulating, and it is doing so faster than previous outbreaks. “There’s reason to expect this virus is here to stay, and it’s not going to disappear,” said Runstadler.

Prof Ian Brown, APHA’s director of scientific services, recently shared his concerns with the BBC. “The virus is absolutely on the march. And it’s almost remarkable – it’s a single strain,” he said, adding that he was “acutely aware of the risks” of avian flu becoming a pandemic like COVID-19.

Bird flu 'spills over' to otters and foxes in UK [BBC, 2 Feb 2023]

By Claire Marshall & Malcolm Prior

The largest ever outbreak of bird flu is spilling over into mammals, including otters and foxes in the UK.

Figures released to the BBC show the virus has led to the death of about 208 million birds around the world and at least 200 recorded cases in mammals.

Public health bosses warn the mutation in mammals could see a jump to humans but the risk to the public is very low.

There will now be more targeted surveillance and testing of animals and humans exposed to the virus in the UK.

The UK Health Security Agency (UKHSA) still advises that avian flu is primarily a disease of birds, but experts across the globe are looking at the risks of it spilling over into other species.

Worldwide, the virus has been found in a range of mammals, including grizzly bears in America and mink in Spain, as well as in dolphin and seals.

In the UK, the Animal and Plant Health Agency (APHA) has tested 66 mammals, including seals, and found nine otters and foxes were positive for highly pathogenic avian influenza (HPAI) H5N1.

Cases have been found in Durham, Cheshire and Cornwall in England; Powys in Wales; Shetland, the Inner Hebrides and Fife, Scotland.

It is believed they had fed on dead or sick wild birds infected with the virus.

The animals were found to have a mutation of the virus that could make it easier to infect mammals, but there was no evidence of transmission between mammals.

The APHA added that there was "a very low likelihood of any widespread infection in GB mammals".

Prof Ian Brown, APHA's director of scientific services, said: "A sick or a dead wild bird contains an awful lot of virus. So scavenging mammals that will be opportunistic and predate on dead or sick birds will be exposed to very large quantities of virus. That gives a possibility for the virus to enter a host population that it doesn't normally maintain in."

Prof Brown said that the UK's national avian flu taskforce was now ramping up its surveillance of cases in mammals and genome analysis of the virus itself while keeping a close eye on its spread in global populations of wild birds.

"The virus is absolutely on the march. And it's almost remarkable - it's a single strain," he said, adding that greater international action to tackle its spread was needed.

He told the BBC he was "acutely aware of the risks" of avian flu becoming a pandemic like Covid-19.

He said: "This global spread is a concern. We do need globally to look at new strategies, those international partnerships, to get on top of this disease.

"If we don't solve the problem across the globe, we're going to continue to have that risk."

Since October 2021, when the latest outbreak began, there have been five confirmed human cases of the H5N1 virus, including one in the UK, and one death, in China.

Last month, a nine-year old girl in Ecuador was found to be infected with avian influenza A(H5).

The World Health Organization (WHO) said that, in the past 20 years, there have been almost 870 cases of human infection with the avian influenza H5N1 virus reported from 21 countries. Of these, 457 were fatal.

It said the virus has "not acquired the ability for sustained transmission among humans. Thus the likelihood of human-to-human spread is low."

But it added: "Due to the constantly evolving nature of influenza viruses, WHO continues to stress the importance of global surveillance to detect and monitor virological, epidemiological, and clinical changes associated with emerging or circulating influenza viruses that may affect human (or animal) health, and timely virus-sharing for risk assessment."

Dr Wenqing Zhang, the head of WHO's global influenza programme, said of the threat posed by the virus spilling over: "It is very concerning and the risk has been increasing over the years as reflected in the number of outbreaks in animals as well as a number of infections in humans."

Intergovernmental organisation the World Organisation for Animal Health (WOAH) told the BBC it has recorded almost 42 million individual cases in domestic and wild birds since the outbreak began in October 2021.

Almost 15 million domestic birds, including poultry, have died from the disease, and more than 193 million more have been culled.

It also shows 119 outbreaks affecting mammals, with about 200 individual cases recorded - although a WOAH spokesperson warned the spread to mammals was likely to be under-reported.

Dr Gregorio Torres, WOAH's head of science, said there had been an increase in reports of non-avian species being affected by the virus over the past 18 months.

He said it "could be a signal of very sensitive surveillance - an indicator that we are doing a good job".

But he added: "On the other hand, it could also be an indicator that there is a change in the epidemiology of the disease or a change in the dynamic of the disease. And that will require close monitoring.

"There is a risk for further transmission between species and we cannot underestimate the potential adaptation to humans."

In a recent report, the UK Health Security Agency (UKHSA) warned that the "rapid and consistent acquisition of the mutation in mammals may imply this virus has a propensity to cause zoonotic infections", meaning it could jump to humans.

The agency also raised concerns about limited wild bird and mammal surveillance and genomic data collection in England, and warned that there was not enough testing of people who had been contact with infected birds.

It is now looking to develop new ways of testing humans who have been exposed to the disease but may be asymptomatic

Dr Meera Chand, incident director for avian influenza at UKHSA, said: "Latest evidence suggests that the avian influenza viruses currently circulating in birds do not spread easily to people. We remain vigilant for any evidence of changing risk.

"There have recently been some detections of avian influenza viruses in a small number of mammals in the UK. However, the risk assessment conducted by UKHSA and partners did not identify any signals of increased risk to the general public from avian influenza at present."

Meanwhile, the public is being warned not to touch any dead or sick birds, but to report any dead birds of prey, three or more dead wild waterfowl or gulls or five or more dead birds of any species that they find to the Department for Environment, Food and Rural Affairs.

Bird flu has jumped to mammals in the UK - so how worried should humans be? [Sky News, 2 Feb 2023]

By Josephine Franks

Bird flu has been found in foxes and otters in the UK and around the globe it's cropped up in dolphins, bears and cats. Does that mean avian flu is heading for humans, and should we prepare for a pandemic? It's not that alarming - but scientists do have warnings.

Why you can trust Sky News
Bird flu has been creeping slowly closer to home since the outbreak started in October 2021.
First there were the headlines about poultry being culled, then the shortage of Christmas turkeys and the barren supermarket shelves where eggs were once stacked high.

Now bird flu has spilled to mammals in the UK, with otters and foxes testing positive for the virus.

With COVID now in its fourth year, people are naturally alert to the possibility of another pandemic sweeping through the population.

Bird flu isn't about to become the next Omicron, but the possibility of the virus mutating means scientists are keeping a watchful eye.

What animals has bird flu been found in?
On Thursday, the Animal and Plant Health Agency (APHA) confirmed five foxes and four otters have tested positive for avian flu in England, Scotland and Wales since 2021.

The UK isn't alone in seeing the virus crop up in mammals. Around the world it's been found in domestic cats, grizzly bears, dolphins, leopards and more, according to the United Nations Food and Agriculture Organisation.

In October last year, mink started dying at a farm in Spain. Testing revealed they had H5N1 avian flu.

How worried should we be about bird flu in mammals?
The spread at the mink farm set alarm bells ringing. In most cases where mammals become ill - including the otters and foxes in the UK - it's likely because they ate infected dead wild birds or their droppings.

But at the mink farm, the virus appeared to spread between the animals, from pen to pen.

Genetic sequencing showed the mink were infected with a new variant of H5N1 which includes a genetic change that means animal-flu viruses are better able to reproduce in mammals,
according to a report by Nature.

A UKHSA risk assessment from January concluded the apparent transmission between mink was of "significant concern" but said there was no "clear evidence" this had happened in any other species of mammal.

When it comes to the strain found in mammals in the UK, there's "currently no reason to suspect that the jump is due to a change in the virus's genetic make-up", according to Dr Alastair Ward, associate professor of biodiversity and ecosystem management at the University of Leeds.

He said foxes and otters are known to scavenge, and it's likely the bird carcasses would have had high viral loads.

"Such high exposure is likely to have overwhelmed the mammal's immune system, resulting in infection," he said.

What does this mean for humans?
Just because bird flu has been found in mammals, it doesn't mean humans are next in line.

As Dr Ward points out: "Humans rarely come into contact with wild foxes or otters, and potentially infectious contact is likely to be rarer still."

Professor Ian Jones, virologist at the University of Reading, said while the jump to different species provides an opportunity for the virus to adapt to mammals, "the natural barriers to this occurring are quite high".

"The risk to people right now therefore appears no more than it is for direct spread from infected birds."


"The risk to people right now therefore appears no more than it is for direct spread from infected birds."

But low risk doesn't mean no risk
The kicker is that phrase "right now". The Pirbright Institute, which carries out research into viral diseases in animals, warns that new avian flu virus strains are created frequently, meaning there is "a constant risk that one of the new strains may spread easily among people".

If this happened, we could be facing a new influenza virus pandemic.

It notes the viruses responsible for all four of the worldwide human influenza pandemics seen in the last 100 years have originated from birds.

What's being done?
The APHA is boosting its surveillance programme to make sure it tracks any instances of the virus passing from mammal to mammal.

Speaking on BBC Radio 4's Today programme, Prof Jones said Defra and the devolved administrations are supporting a programme for actively looking for mammals that we believe might scavenge and feed on wild birds.

"We analyse those viruses if we detect them, and we share that data very rapidly with our public health counterparts, so we can make clear and rapid assessments."

He added: "If you analyse the genetic code of the virus, you can work out whether it's come from a bird or whether it's going from one mammal to another."

Bird Flu Warning: Its Spreading, Mutating, and Infecting Mammals [Infection Control Today, 24 Jan 2023]

By Kevin Kavanagh

As many of us remain focused on COVID-19 and its immunosuppressive augmentation of other infectious diseases, mother nature is not sitting still. I was again reminded of this fact when I attempted to purchase a dozen eggs for over $6. The average price in the United States was over $4 in December 2022. In January 2023, the New York Timesreported a cost of over $7. This consumer price gouge is not the grocery store's fault, the COVID-19 bailout, or even our bloated federal deficit. It is the result of mother nature and the H5N1 bird flu pandemic.

Along with RSV, SARS-CoV-2, and Seasonal influenza, the bird flu is spreading rapidly in the United States at epidemic proportions. According to the New York Times, 60 million birds have been infected or killed (culled) in 47 states. So far, this has surpassed the second-largest outbreak in 2015, when 50.1 million birds died in 21 states. The number of states affected has more than doubled.

Bird flu has rarely affected humans; when it does, it is from directly handling birds. The virus rarely spreads from human to human. The concern is that when it infects humans, according to the Centers for Disease Control and Prevention (CDC), there is an approximately. From 2003 to 2006, H5N1 infected 232 people and killed 134.

But the one thing we have all learned from COVID-19 is that when RNA viruses spread rapidly, they mutate. This is what appears to have happened with H5N1. A new strain that is “highly pathogenic” has emerged and killed 1,600 snow geese in Colorado. To make matters worse, 3 Montana grizzly bears had to be euthanized after they caught the virus. This outbreak was described as the most significant foreign animal outbreak in US history and raises fears that the virus has mutated to promote the infection of mammals. A capability that could have profound consequences for the mammalian species, homo sapiens.

Unfortunately, this outbreak appears not to be a single occurrence. In Spain, a highly pathogenic H5N1 virus has infected the mink population. As of early October 2022, 52,000 minks were placed in cages, and the expected overall mortality of 0.2% to 0.4% rose to a mortality rate of 4%. Samples from the minks that died revealed the H5N1 virus. This virus was also found in 27 birds in the province and a neighboring province. The authors report that mink-to-mink transmission has occurred.

The virus which affected the mink population was a new strain, having the “uncommon mutation (T271A) in the PB2 gene.” Zhang Y et al (2012) have observed, “that amino acid 271A of PB2 plays a key role in virus acquisition of the mutation at position 226 of HA that confers human receptor recognition.” In other words, the strain which infected the mink population may be one step away from being able to spread in humans efficiently.

There have also been several gain-of-function laboratory experiments which, as dangerous as these experiments are, have shown the potential for the avian flu virus to take on characteristics of seasonal influenza. In 2006, CDC made 2 hybrid viruses (avian flu and human influenza) and infected ferrets, but the infection failed to spread. But research reported in 2010 by Dr. Yoshihiro Kawaoka from the University of Wisconsin produced a highly pathogenic hybrid with the pandemic ability of H1N1 (human influenza). The report states, “the new findings raise concerns that H5N1 and pandemic H1N1 viruses could reassort in individuals exposed to both viruses and generate an influenza strain that is both highly virulent and contagious.” The published research in the Proceedings of the National Academy of Sciences also stressed the importance of monitoring the emergence of avian flu viruses with mutations in the PB2 segment.

“…that the human virus PB2 segment functions in the background of an avian H5N1 virus, enhancing its virulence. Our findings highlight the importance of surveillance programs to monitor the emergence of human H5 reassortant viruses, especially those containing a PB2 segment of human origin.”

I’m starting to experience dé·jà Vu. Gain-of-Function experiments performed on a hazardous virus, viral spread from birds to mammals, spread between mammals, and mutations beginning to arise, which may be the first step in conferring the ability to transmit in humans.

I do not want to go through this again, especially since our current pandemic is not under control. We need to aggressively contain the spread of bird flu and increase our genomic surveillance for this disease. This is not a certainty since our current genomic surveillance for COVID-19 needs to be strengthened at a time when mutations are flourishing, and the dangers of long COVID are becoming more ominous.

Mass death of seals raises fears bird flu is jumping between mammals, threatening new pandemic [iNews, 1 Feb 2023]

By Jane Merrick

Avian flu has been found in seals that died a ‘mass mortality event’ in the Caspian Sea. Now scientists are investigating whether it is the first transmission of the virus between mammals in the wild

Scientists are investigating the possibility that bird flu has been transmitted between mammals in the wild for the first time – fuelling fears it could lead to the next pandemic in humans.

In what is being described as a “mass mortality event”, more than 700 seals were found dead in December in the Caspian Sea, near to where the highly contagious H5N1 variant of avian flu was found in wild birds months earlier.

Scientists from Dagestan State University have identified bird flu in tissue from the dead seals, although it is too early to say whether it was the cause of death or if the animals transmitted it to each other.

The situation is being monitored by the UK Government, i has learned, with Defra and the UK Health Security Agency being given regular updates.

Individual seals and other mammals have previously been infected with avian flu directly from birds, but up until now the only recorded incidents of it transmitting between mammals is among mink bred in close quarters in captivity at a farm in Spain.

If the H5N1 variant has adapted to pass between mammals, virologists fear that it could make a further evolutionary jump to become transmissible between humans and trigger a pandemic.

There is currently no evidence that the virus can pass between humans. Since the latest global outbreak of H5N1 began a year ago, fewer than 10 people have caught the virus, directly from close contact with poultry or other birds, and only one human death has been reported.

But samples from four mink which caught H5N1 in an outbreak at a mink farm in Galicia, northwestern Spain, in October revealed changes in the virus, including a mutation called T271A which can more easily replicate in mammalian tissue.

If it is confirmed that bird flu was passed between the seals in the Caspian Sea, it would be the first known transmission between mammals in the wild.

Dr Tom Peacock, a virologist at Imperial College London, told i: “If this turns out to be sustained transmission in a wild mammalian species this is yet another worrying ‘first’ with these H5N1s that shouldn’t be ignored. It would be yet more evidence these H5N1s could be poised to cause the next pandemic.”

Defra is aware of the developments in the Caspian Sea and the report by Dagestan State University that it has identified avian flu in seal tissue, i understands.

The latest risk assessment from the UK Health Security Agency is that the risk to the human population from bird flu is “very low”, but that there is evidence that the H5N1 strain has evolved to become more easily replicated in mammals.

The current threat is Level 3, that there is “evidence of viral genomic changes that provide an advantage for mammalian infection”, which is one below Level 4, evidence of sustained mammal-to-mammal transmission, and two below Level 5, human-to-human transmission.

H5N1 has been responsible for the deaths, from both infection and culling, of millions of birds in the UK and globally, with farmers ordered to bring free range turkey and other poultry indoors from last autumn.

In the waters around Britain, stranded seals are collected and any possible cause of death is investigated for disease including avian flu. No seals, dolphins or whales have yet tested positive for bird flu around Britain during the current outbreak, which began in December 2021, but there have been previous cases in these sea mammals.

The UKHSA has advised people not to handle sick or dead poultry or other birds.

Announcing that avian flu had been identified in the Caspian seals, Dagestan State University said: “Preliminary studies of the mass mortality of Caspian seals showed that the animals were infected with avian influenza. At the same time, it is too early to conclude that it was the virus that caused the death, research is ongoing.”

Alimurad Gadzhiev, director of the Institute of Ecology and Sustainable Development at DSU, said: “Specialists of the Institute of Ecology and Sustainable Development, together with colleagues from the Research Institute of Virology and experts from the Compass Foundation, took tissue samples from dead seals in December to determine the causes of death. Based on the first results, we can say that the samples tested positive for bird flu.”

The incident in Dagestan was first reported by the Avian Flu Diary blog, which said: “While we’ve seen a number of different influenza A viruses infect seals in the past – including H3N8, H10N8, H7N7, etc. – HPAI H5N1 is the most obvious suspect right now. Hopefully we’ll get confirmation in the days ahead.”

An ‘unprecedented pandemic of avian flu’ is wreaking havoc on the U.S. poultry industry. Humans may be at risk too, experts warn [Fortune, 24 Jan 2023]

BY ERIN PRATER

The H5N1 strain of avian flu responsible for the deaths of tens of millions of birds in the U.S. in recent months, and countless more worldwide, poses an existential threat to the poultry industry in the U.S.—and a potentially widespread human health threat, experts say.

The strain—first identified in domestic waterfowl in China in 1996—is behind nearly 58 million U.S. bird deaths in the past year. These deaths have occurred both directly due to the virus and indirectly, when flocks are culled to curb further exposure, according to the U.S. Centers for Disease Control and Prevention. The virus has a near 100% fatality rate among birds, killing most infected within 48 hours.

This season’s bird flu outbreak is the worst in U.S. history, having surpassed a 2015 outbreak the CDC once called “arguably the most significant animal health event in U.S. history.” That year, nearly 51 million birds died nationally due to H5N1 and related avian flu viruses. This season’s outbreak is also the worst in U.K. history, with farmers in England ordered to keep their birds indoors as of Nov. 7 in a poultry “lock down” of sorts.

The so-called “R naught” value—or the number of people infected by a single infected person, on average—for COVID initially ranged from 1.5 to 7, and now sits upwards of 12.

The R naught value of H5N1 among birds: “around 100,” according to Chowdhury.

It’s an environmental crisis already impacting humans, sending the price of poultry skyrocketing and making eggs harder to come by. U.S. egg retail costs have doubled over the past year, and oven-ready chicken prices are up by a quarter or more in the U.K., Bloomberg recently reported.

“The world is facing an unprecedented pandemic of avian flu among caged and wild bird populations,” Rajiv Chowdhury, senior epidemiologist and professor of global health at Florida International University, tells Fortune.

What’s more, the poultry industry likely cannot “sustain itself in countries like the U.S. if we continue to see annual surges,” Dr. Michael Osterholm, director of the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP), adds.

Economic and food-supply issues aside, the strain has sickened people, too, albeit in small numbers so far. But the trend of minimal transmission among humans may not hold, experts warn. Last week the WHO reported that a previously healthy Ecuadorian girl had been hospitalized with the virus. Just how she contracted the virus is uncertain and under investigation, but poultry her family had recently purchased died without apparent cause.

Oserholm and Chowdhury are concerned about additional spread from birds to humans, and about possible transmission from humans who contract the bird flu to other humans—especially as the virus traverses the globe and makes the leap to more mammals, due to mutations.

Last week the first grizzlies to be documented with the highly pathogenic avian flu were euthanized in Montana after they were found partially blind and disoriented, with other neurologic issues. Foxes, dolphins, opossums, skunks, seals, other types of bears, and a bottlenose dolphin are among other species that have been infected since last year, according to the U.S. Department of Agriculture.

The likelihood of human-to-human transmission of H5N1 is “very low,” Chowdhury says. But if it were to occur in a sustained manner, it could rock the globe in a way not seen since the 1918 Spanish Flu.

If H5N1 indeed makes a sustained crossover to humans, “the potential impact could be significant,” he says, signifying the start of a “new global influenza pandemic.”

‘Unusual’ among humans, but highly fatal
The virus’s Ecuadorian victim—the country’s first, as well as the first in the Latin America/Caribbean region—was admitted to a hospital for symptoms of nausea, vomiting, and constipation on Dec. 30, where she was presumptively treated for meningitis, according to a Jan. 18 WHO disease outbreak update.

On Jan. 3, she was transported to a pediatric hospital in critical condition after suffering septic shock and being diagnosed with pneumonia. She tested positive for the H5N1 strain on Jan. 7 and remained hospitalized, under sedation and on a ventilator as of Jan. 17, the international health organization stated.

The previously healthy girl becomes the seventh individual the virus has sickened since 2020, according to the World Health Organization. While H5N1 is considered highly infectious, that’s only among birds. It’s typically difficult for the virus to make the leap to humans, and transmission from human to human is “unusual,” the international health organization says.

When the virus does make the leap, however, it’s highly fatal, with a mortality rate of greater than 50% among humans, according to the CDC.

H5N1 outbreaks have come and gone throughout a quarter century, without sustained transmission in humans, Osterholm points out. Hundreds of human cases were identified in Egypt earlier this century, though there was no sustained human-to-human transmission. The virus’ track record gives reason to hope that transmission to humans, and among them, will remain the exception rather than the rule.

Chowdhury says the 1918 flu pandemic, however, serves as a cautionary tale. Like the H5N1 flu, the Spanish Flu is thought to have avian origins. Both viruses contain genes that allow them to replicate efficiently in human bronchial cells, according to a 2006 report from the Washington, D.C.-based Population Reference Bureau.

In the case of H5N1 among humans, such inflammation can lead to lung cells becoming “intensely inflamed”—much more so than would be seen in a usual flu. A similar effect was noted in Spanish Flu victims, autopsies of which revealed “lungs choked with debris from the excessive inflammation,” resulting in drowning, the report noted.

While seasonal flu symptoms include fever, cough, sore throat, runny nose, aches, and fatigue, according to the CDC, symptoms of H5N1 in humans are typically much more severe. They include an often high fever, weakness, cough, sore throat, and muscle aches, abdominal pain, chest pain, and diarrhea, according to the WHO. These symptoms can quickly give way to difficulty breathing, pneumonia, and/or Acute Respiratory Distress Syndrome, which is often deadly, as well as neurologic effects like seizures.

The seasonal flu vaccine doesn’t cover H5N1, according to the WHO. And while candidate vaccines for the viral strain have been developed, “they are not ready for widespread use,” according to the organization.

When it comes to planning for the next pandemic, influenza has always been considered a likely culprit, Dr. Georges Benjamin, executive director of the American Public Health Association, tells Fortune.

While the Ecuadorian girl and her disturbing bout with H5N1 “may very well be a one-off” case, “we could easily have an H5N1 or another pandemic of influenza,” he says.

“It should scare you.”

While there’s currently no reason to suspect sustained H5N1 transmission among humans, the outlook may not be so hopeful for the U.S. poultry industry, which is in “deep trouble right now,” Osterholm tells Fortune.

“They’ve got to change biosecurity procedures,” he says, adding that the virus can’t be kept away from flocks simply by “putting a screen up” because it’s transmitted in an airborne manner.

“These barns are going to require a great deal more air-handling considerations,” he adds.

“H5N1 has fundamentally rewritten avian influenza.”

Avian flu outbreak at Spanish mink farm sets off global alarm bells [EL PAÍS USA, 24 Jan 2023]

By MANUEL ANSEDE

Research on a case that occurred three months ago suggests that the virus jumped from wild birds and mutated at the facility, where all the animals were culled

It’s like a script for a disaster movie that everyone has already seen. Europe is going through the most devastating bird flu epidemic in its history, with more than 50 million poultry slaughtered in one year. At the beginning of autumn, seagulls and gannets killed by this virus appeared on the beaches of Spain’s northwestern Galicia region. Days later, in early October, American mink began to die of hemorrhagic pneumonia on a fur farm in Carral, a few minutes’ drive from the city of A Coruña. Mortality in this outbreak exceeded 4% in a single week.

A scientific study now suggests that the avian flu virus jumped from wild birds to mink and mutated on the farm, beginning to spread from mammal to mammal but failing to infect mask-wearing farm workers. This outbreak has set off alarm bells across the planet. The Dutch virologist Marion Koopmans, who traced the origin of the Covid pandemic for the World Health Organization (WHO), has issued a warning on her social media accounts: “We are playing with fire.”

The British doctor Jeremy Farrar, an expert in emerging diseases who was recently appointed chief scientist at the WHO, has also alerted about the recent outbreak in Spain on his social media. “The greatest risk of a devastating flu pandemic is avian or animal flu that infects intermediate mammals, and evolves to mammal-to-mammal and human-to-human transmission with little or no human immunity,” he said on Twitter. Farrar, who correctly alerted the world to a strange pneumonia in the Chinese city of Wuhan on December 31, 2019, is now urging authorities to prepare vaccines and treatments for each type of animal flu.

A mixing vessel
Mink are susceptible to both bird flu and human flu, so these animals can act as a mixing vessel in which viruses mix and more lethal versions emerge, warns the study, which was led by Montserrat Agüero of the Central Veterinary Laboratory of Spain’s Ministry of Agriculture and her Italian colleague Isabella Monne, from the Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe).

The culprit in the Galician outbreak is a highly pathogenic avian influenza A (H5N1) virus, with an unusual mutation called T271A, a disturbing characteristic that was already present in the swine flu virus that caused a pandemic in humans in 2009. Regional health authorities decided on October 18 to immediately cull the 52,000 mink on the farm, located outdoors and with easy access to wild animals.

Virologists’ worst nightmare would be the leap to humans of a deadly flu virus. The WHO had already warned in 2019, before Covid, that “the world is not prepared for a pandemic of virulent and rapidly transmitted respiratory pathogens.” The institution then said that a pandemic such as the 1918 flu could kill 80 million people, “causing panic, destabilizing national security and seriously affecting economy and trade.”

It’s pretty scary. In Europe there had never been such an outbreak in mink before
Elisa Pérez, virologist

The virologist Elisa Pérez, an expert in emerging viruses at Spain’s Animal Health Research Center (INIA-CISA), is very concerned. “It’s pretty scary. In Europe there had never been such an outbreak in mink before, there were only a few cases described in China. We had never had such a big scare,” she warns. Pérez would like for all mink farms to be shut down as soon as possible. “What else needs to happen?”

Before the Covid pandemic, there were around 2,900 fur farms in the European Union, producing 27 million mink pelts each year, according to official industry figures. After the coronavirus outbreaks in hundreds of farms in 2020, some countries, such as Denmark and the Netherlands, ordered massive culls and closures. A report by European authorities estimated that there were 755 mink farms left in operation at the start of 2021, mainly in Finland, Poland, Lithuania and Greece. In Spain, that crisis caused some security measures to be implemented, such as mandatory face masks for workers.

One of the mink from a Dutch farm where Covid cases were recorded.

Bird flu is spreading around the world. The virus has already settled in South America, a team of scientists from Argentina and Peru warned last week. On the Peruvian coasts, 22,000 wild birds died in just one month, especially pelicans and boobies. On January 9, a nine-year-old girl from a village in Bolívar (Ecuador), admitted to intensive care after being in contact with chickens, became the first human case of highly pathogenic avian influenza in Latin America.

The WHO warned last Wednesday that the diversity of flu viruses that are jumping from animals to people is “alarming.”

In Spain last year there were 37 outbreaks of highly pathogenic avian influenza in poultry, the last two in a farm with 150,000 laying hens in Guadalajara and in another with 1,500 geese in La Cistérniga (Valladolid), according to figures provided by the Ministry of Agriculture. Two workers at the Guadalajara farm became infected with the virus without developing symptoms. In the Carral outbreak, the 11 employees who were in contact with the mink remained in isolation for 10 days, despite having tested negative for avian flu.

The virus is easily transmitted between birds, but only rarely does it pass from bird to human. Between people it has not yet managed to jump effectively, although the outbreak in mink in A Coruña suggests that the virus is capable of mutating and adapting rapidly to jumping from mammal to mammal.

The epidemiologist Matthew Baylis, former director of The Pandemic Institute in Liverpool, has also reacted to the analysis of the Galician outbreak. “Two years ago I wrote about the risks of mink farming for Covid. And now we see even greater risks for avian influenza, as mink provide a wonderful opportunity for the virus to adapt to mammals. This is where the next pandemic may come from,” he tweeted. “Is anyone heeding the warning sign? Clearly not.”

'Incredibly concerning': Bird flu outbreak at Spanish mink farm triggers pandemic fears [Science, 24 Jan 2023]

BY KAI KUPFERSCHMIDT

Spread among captive mink could give the H5N1 strain opportunities to evolve and adapt to mammals

When mink at a big farm in Galicia, a region in northwestern Spain, started to die in October 2022, veterinarians initially thought the culprit might be SARS-CoV-2, which has struck mink farms in several other countries. But lab tests soon revealed something scarier: a deadly avian influenza virus named H5N1. Authorities immediately placed workers on the farm under quarantine restrictions. The more than 50,000 mink at the facility were killed and their carcasses destroyed.

None of the farm workers became infected. But the episode, described in a paper in Eurosurveillance last week, has reignited long-smoldering fears that H5N1 could trigger a human pandemic. The virus is not known to spread well between mammals; people almost always catch it from infected birds, not one another. But now, H5N1 appears to have spread through a densely packed mammalian population and gained at least one mutation that favors mammal-to-mammal spread. Virologists warn that H5N1, now rampaging through birds around the world, could invade other mink farms and become still more transmissible.

“This is incredibly concerning,” says Tom Peacock, a virologist at Imperial College London. “This is a clear mechanism for an H5 pandemic to start.” Isabella Monne, a veterinary researcher at the European Union’s Reference Laboratory for Avian Influenza in Italy, where the samples from Spain were sequenced, calls the finding “a warning bell.”

H5N1 was first detected at a goose farm in China in 1996. A big poultry outbreak in Hong Kong in 1997 led to the first documented human deaths and sparked the first pandemic fears.

Around 2005, the virus spilled over into migratory birds, which have since spread it across the world in several big waves. A new variant named 2.3.4.4b that emerged in 2020 has spread faster and farther than any predecessor, dealing huge blows to the poultry industry in Europe and North America before arriving in Central and South America in the fall of 2022. “It seems this virus is just more adapted to all birds than any others have been,” says Richard Webby, an influenza researcher at St. Jude Children’s Research Hospital.

Because the receptors the virus binds to in the upper airways of birds are less common in mammalian upper airways, H5N1 largely spares mammals. But this time around many mammalian species have become infected, including foxes, cats, ferrets, seals, and dolphins, presumably through contact with infected birds. On 17 January, Montana authorities said three juvenile grizzly bears euthanized in the fall after becoming very sick were infected with H5N1 as well. People have caught it, too. So far there have been six confirmed human infections in the current global wave, including one death.

There are some signs that 2.3.4.4b is less pathogenic in humans than earlier versions, which killed roughly half of those infected, says Thomas Mettenleiter, head of the Friedrich Loeffler Institute. “Of course that can be bad news, too, because it might make it easier for the virus to start spreading under the radar, giving it more opportunity to evolve,” he says. The more often the virus infects mammals, the greater the risk, Webby says. “It’s a numbers game.”

There have been some past reports of avian influenza outbreaks on mink farms in China, but no clear evidence that the virus spread between the animals. In the Spanish outbreak, there seems to be little doubt it did. In theory, all of the sick animals could have picked up the virus from their feed, which included poultry byproducts, but H5N1 outbreaks have not been reported in the region where the poultry farms and slaughterhouses supplying the feed are located. And the virus spread from pen to pen as expected if it was transmitted between mink.

The chain of infections might have begun after one animal caught a sick bird and pulled it into its cage, says Thijs Kuiken, a veterinary pathologist at Erasmus University Medical Center.

How readily the virus found in Spain might infect humans—or spread between them—is unknown. Sequenced virus samples from four mink show several changes compared with the bird virus, including T271A, a mutation in the gene for an enzyme, polymerase. The change, also seen in viral samples from other infected mammals, is known to help H5N1 better replicate in mammalian tissues. E627K, another worrisome mutation in the polymerase gene, has not emerged, however, and the gene for hemagglutinin—a protein on the viral surface that latches on to the host ¬receptor—has not changed, Peacock says. “We may still have been lucky with this one.”

Monne says her team and others are now studying the properties of the mink virus and the effects of the mutations it has accumulated. Among other things, they want to study how well the virus transmits through close contact between animals. “We are planning to also do aerosol transmission studies,” she says.

The outbreak again puts the spotlight on the risks of mink farming. SARS-CoV-2, introduced at farms by humans, spread like wildfire among the animals but was also passed back to their caretakers, and researchers worried the mink industry might become a permanent source of infections and a breeding ground for genetic variants. The Netherlands, which had already decided to phase out mink farming by 2024 for ethical reasons, closed all remaining farms in 2021. Denmark culled all mink in the country in 2020, but a ban on mink farming expired at the beginning of this year.

The farms pose just as big of a threat when it comes to H5N1, Kuiken says. Most of the mammalian species infected with the virus so far are wild predators and scavengers feeding on infected birds—“solitary animals, or animals that live in small families,” he says. They are unlikely to spread the virus far or infect humans. At mink farms, thousands of such solitary carnivores are forced to live together, creating ideal conditions for the avian virus to adapt to mammals. “It’s a human construct,” Kuiken says.

At the very least, biosafety measures on mink farms need to be tightened, Monne says. Farm workers should wear masks and take other measures to prevent infection, and the farms should reduce the risk of accidental H5N1 introductions. “They should be really carefully keeping the animals far away from wild birds.” Peacock says perhaps it’s time to just end mink farming. “That this is happening in Europe in this day and age, and after COVID-19, is doing my head in,” he says. “It’s a bit of an existential threat.”

Mink-farm outbreak shows bird flu can spread between mammals [Nature.com, 24 Jan 2023]

BY Saima May Sidik

A new variant of H5N1 influenza could pose an increased risk to people and wild animals.

An outbreak of avian influenza on a mink farm in Spain provides the strongest evidence so far that the H5N1 strain of flu can spread from one infected mammal to another.

The outbreak of H5N1 flu, described in a report in Eurosurveillance on 19 January1, occurred on an American mink (Neovison vison) farm in Carral in October 2022. Genetic sequencing showed that the animals were infected with a new variant of H5N1, which includes genetic material from a strain found in gulls, as well as a genetic change known to increase the ability of some animal-flu viruses to reproduce in mammals.

The new variant puts bird flu in “uncharted territory”, says Wendy Puryear, a virologist at Tufts University in Medford, Massachusetts. Researchers have warned that, without careful precautions, the disease might eventually spread among people.

Jumping species
Over the past year, H5N1 has shown an increasing ability to jump from birds to mammals. In the United States, infections have been found in about a dozen species, including raccoons, foxes, seals and grizzly bears.

Until this particular outbreak, all mammalian infections could be attributed to direct contact with virus-contaminated material, says Hualan Chen, a virologist at the Harbin Veterinary Research Institute in China. For example, animals that ingest wild-bird droppings, or that prey on infected animals, can develop the disease. But its spread between mammals “implies that this H5N1 virus may pose a higher risk to public health”, Chen says.

During the first week of October 2022, workers on the affected mink farm noticed that the minks’ mortality rate had increased from a baseline of 0.25% per week to 0.77%, prompting tests on the affected animals for the H5N1 and SARS-CoV-2 viruses. The animals tested positive for H5N1. In the following weeks, more animals fell sick, and the disease seemed to spread from ‘hot spots’ of between two and four pens, in which all animals became infected and died. Workers were forced to cull all 51,986 mink on the farm. Eleven farm workers were in contact with the infected mink, but all tested negative for H5N1.

“This species could serve as a potential mixing vessel for the interspecies transmission among birds, mammals and human,” the report’s authors write. “It is necessary to strengthen the culture of biosafety and biosecurity in this farming system and promote the implementation of ad hoc surveillance programs for influenza A viruses and other zoonotic pathogens.”

Preventing spread
Measures taken to prevent the new strain from spreading beyond the farm seem to have been “vigorous, comprehensive and successful”, says infectious-disease specialist William Schaffner at Vanderbilt University Medical Center in Nashville, Tennessee.

But Puryear thinks that because the new variant contains genetic material from gull flu, it’s likely that at least some of its genetic changes arose in gulls before entering the mink farm.

This means that a strain containing those mutations is probably still circulating in the bird population. But for human populations, the outlook is still good: if the new strain did start to infect people, health authorities could probably produce a vaccine quickly, and the antiviral drug Tamiflu can reduce the severity of the disease.

The potential risk to wild animals is greater. Bird flu has consistently caused high levels of sickness and death among wild birds and mammals over the past year, and how the new variant will affect that trend remains to be seen. “We just simply don’t know,” says Puryear.
References

1. Agüero, M. et al. Eurosurveillance 28, 2300001 (2023).