Zoonotic Bird Flu News since 9 Feb till 10 Feb 2023

More than 500 sea lions die from bird flu in Peru [Euronews, 10 Feb 2023]

By Rosie Frost

Hundreds of sea lions have died of bird flu in Peru in recent weeks, authorities say, urging people to stay away from the beaches.

It is thought that migratory birds from the US were responsible for transmitting the disease.
55,000 dead birds including pelicans and penguins have been discovered across eight protected coastal areas, the Sernanp natural area protection agency said.

Wildlife rangers in the region found that the bird flu which killed them had also claimed the lives of 585 sea lions in seven different protected marine areas. Lab tests confirmed the presence of the virus in these animals, prompting authorities to announce a “biological vigilance protocol”.

Peru's National Forest and Wildlife Service (SERFOR) has urged people and their pets to avoid contact with sea lions and seabirds on the beach.

In November, Peru declared a 180-day health alert after finding three cases of highly contagious bird flu in pelicans.

Then, in December, 37,000 birds on a chicken farm were culled after a previous outbreak affected wildlife. Killing the birds is a part of standard protocol to prevent the spread of avian influenza.

Is bird flu a risk to humans?
It is rare that the H5N1 bird flu virus jumps over to mammals and even rarer that humans catch it. But recently it has been found in foxes and otters in Britain, a cat in France and grizzly bears in Montana, US.

All of the mammals that caught the virus are thought to have eaten infected birds.

Since late 2021, Europe has been gripped by the worst-ever outbreak of the virus. North and South America have seen severe outbreaks too.

By Rosie Frost with AFP ? Updated: 10/02/2023 - 12:36

Hundreds of sea lions have died of bird flu in Peru in recent weeks, authorities say, urging people to stay away from the beaches.

It is thought that migratory birds from the US were responsible for transmitting the disease.

55,000 dead birds including pelicans and penguins have been discovered across eight protected coastal areas, the Sernanp natural area protection agency said.

Wildlife rangers in the region found that the bird flu which killed them had also claimed the lives of 585 sea lions in seven different protected marine areas. Lab tests confirmed the presence of the virus in these animals, prompting authorities to announce a “biological vigilance protocol”.

Peru's National Forest and Wildlife Service (SERFOR) has urged people and their pets to avoid contact with sea lions and seabirds on the beach.

? Fur farming: Here's which EU countries still support the industry
? World’s oldest dog narrowly escaped death as a puppy, owner reveals

In November, Peru declared a 180-day health alert after finding three cases of highly contagious bird flu in pelicans.

Then, in December, 37,000 birds on a chicken farm were culled after a previous outbreak affected wildlife. Killing the birds is a part of standard protocol to prevent the spread of avian influenza.

Scientists at the Paracas National Reserve are deploying a monitoring and surveillance protocol for cases of bird flu.SERNANP / AFP

Is bird flu a risk to humans?
It is rare that the H5N1 bird flu virus jumps over to mammals and even rarer that humans catch it. But recently it has been found in foxes and otters in Britain, a cat in France and grizzly bears in Montana, US.

All of the mammals that caught the virus are thought to have eaten infected birds.

Since late 2021, Europe has been gripped by the worst-ever outbreak of the virus. North and South America have seen severe outbreaks too.
? Wildlife Photographer of the Year: ‘Dream’ shot of elusive snow leopard wins people’s choice award
? Beavers are returning to London - and they might protect a local train station from flooding
World Health Organisation director general Tedros Adhanom Ghebreyesus warned on Wednesday that these cases of H5N1 in mammals must be “closely monitored”.

He said that the risk to humans was currently low but “we cannot assume that that will remain the case and we must prepare for any change in the status quo.”

Ghebreyesus cautioned people against touching sick or dead animals and encouraged those who find them to report them to local authorities.

As Bird Flu Spreads to Mammals, Health Officials Urge Caution [Smithsonian Magazine, 10 Feb 2023]

By Will Sullivan

Transmission between minks has called attention to the potential risks to humans, though experts say not to panic

Amid a global bird die-off from avian flu, officials have also noticed the deadly virus strain, called H5N1, infecting a growing number of mammals. This week, the World Health Organization (WHO) urged authorities to remain vigilant?but not panic?about the virus’s potential risk to humans.

“The recent spillover to mammals needs to be monitored closely,” Tedros Adhanom Ghebreyesus, the WHO’s director-general, told reporters on Wednesday, according to the Agence France-Presse (AFP). But “for the moment, WHO assesses the risk to humans as low.”

Avian flu is not adapted to infect people, making human cases rare and person-to-person transmission even more difficult. But experts say that the more H5N1 spreads among animals, the more likely it is to evolve into a variant that can jump to humans, per the AFP.

Despite the current low risk to public health, officials must prepare “to face outbreaks in humans, and be ready also to control them as soon as possible,” Sylvie Briand, director of Global Infectious Hazard Preparedness and Emergency Preparedness at the WHO, tells Fortune’s Erin Prater.

H5N1 was first detected in domestic waterfowl in 1996 and spread to migratory birds around 2005. Then, these long-distance fliers carried the virus across the world, writes Science’s Kai Kupferschmidt. Over that time, the virus has infected relatively few humans?but those cases have proven deadly. According to the WHO, there were 868 global cases of H5N1 in humans between January 2003 and November 2022, 457 of which were fatal.

Currently, a massive outbreak of bird flu is taking place around the world. The United States is experiencing the worst avian flu outbreak in its history, with the virus directly or indirectly leading to 58 million bird deaths in the past year, per Fortune. Europe is also experiencing its most severe outbreak, according to the AFP.

“With high levels of transmission we are seeing unprecedented numbers of dead birds and outbreaks,” Michelle Wille, a bird flu researcher at the University of Sydney in Australia, tells the Sydney Morning Herald’s Liam Mannix.

H5N1 doesn’t tend to infect mammals, because they have fewer of the receptors in their upper airways that the virus binds to.

But during this year’s outbreak, foxes, raccoons, bears and other mammals have caught the virus. In the U.S., mammalian infections have been detected in nine different states, according to USA Today’s Adrianna Rodriguez. In Peru, at least 585 sea lions have been found dead, likely due to bird flu. Other infected animals include dolphins and opossums, per Fortune.

Most of these cases are probably caused by a mammal eating an infected bird, Jurgen Richt, who studies avian flu at Kansas State University, tells USA Today. But in a paper published in January in the journal Eurosurveillance, researchers document evidence that the virus might have spread between minks on a farm in Spain last October. Genetic sequencing revealed a genetic change known to make some influenza viruses more capable of reproducing in mammals, writes Nature News’ Saima May Sidik.

The mink outbreak “confirmed a fear that I had” that bird flu could spread efficiently in mammals, Thijs Kuiken, a veterinary pathologist at Erasmus University Medical Center in the Netherlands, tells the Times.

“We’ve never seen mammal-to-mammal transmission, ever. It has never happened,” Wille says to the Sydney Morning Herald. “Now it’s no longer just a hypothetical. Now we’ve actually seen it happen.”

Experts say this development is not a cause for alarm. “It’s not, in my mind, a particularly worrisome situation for human health,” Jim Lowe, a veterinarian at the University of Illinois at Urbana-Champaign, tells the Times. “Obviously it’s not very good for the mink.”

The tightly packed, caged minks could have transmitted H5N1 due to their conditions rather than a fundamental change in the virus, Frank Wong, a bird flu expert at Australia’s Commonwealth Scientific and Industrial Research Organization, tells the Sydney Morning Herald. “It’s still a bird-adapted virus.”

But evidence of spread between mammals is also a warning sign, others say. “This outbreak signals the very real potential for the emergence of mammal-to-mammal transmission,” Wille told the CBC News’ Lauren Pelley in an email.

“We need to be vigilant to make sure that spread in animals is contained,” Briand tells the AFP.

“The more the virus circulates in animals, the higher is the risk for humans as well.”

Largest observed bird flu outbreak in Europe to date: Scientists concerned spread to mink signals growing threat to humans [The Indian Express, 9 Feb 2023]

By Deutsche Welle

A bird flu outbreak on a Spanish mink farm has alarmed scientists. The virus may be spreading for the first time from mammal to mammal ? and could become a danger for humans.

It started in October 2022, when several dead mink were discovered on a farm in Galicia in northwestern Spain. Veterinarians initially blamed the coronavirus. But tests revealed that the highly pathogenic avian flu virus H5N1 was the culprit.

To stop the spread of the dangerous pathogen, more than 50,000 mink on the farm were killed. While farm workers themselves were not infected, the case remains a cause of concern for scientists.

Why is the mink farm outbreak ‘incredibly concerning’?
The spread of the virus from birds to other species is nothing new. The pathogen that causes bird flu, or avian influenza, has been found in raccoons, foxes and seals, though these remain isolated cases.

While there have been some cases of H5N1 infecting humans, the World Health Organization has said there’s no evidence of human-to-human transmission so far.

When the disease has spread to humans and other mammals, it has been via direct contact with excrement from infected birds or their carcasses, according to Timm Harder, an avian influenza expert at the Friedrich Loeffler Institute’s diagnostic virology department in Germany.

But the mink outbreak appears to be a rare case where mammals are transmitting the disease to each other rather than through direct contact with an infected bird. This is something “new,” said Harder.

Part of the problem is that mink are intensively farmed. They’re kept in high numbers in confined spaces, which means infection spreads rapidly in the highly susceptible mammals, said Harder.

Harder added that researchers have identified several pathogen mutations in the mink, one of which allows “the virus to better reproduce in mammals.”

Scientists are worried that the virus, which has led to the deaths of tens of millions of birds globally, could spread to more mink farms and become “more transmissible.”

“This is incredibly concerning,” said Tom Peacock, a virologist at Imperial College London, in an interview with the scientific journal, Science. “This is a clear mechanism for a H5 pandemic to start.”

Could avian influenza trigger a human pandemic?
Of the 868 known cases of H5N1 infection in humans worldwide between January 2003 and November 2022, 457 were fatal, according to the WHO.

However, because there has been no sustained human-to-human transmission, the risk of human infection from avian flu is low, said the WHO.

Some highly pathogenic avian influenza viruses have an increased potential to cause new zoonotic diseases ? which are transmissible from animals to humans and vice versa.

While Timm Harder said there are “numerous hurdles for a more extensive adaptation to humans,” he added the mutations seen in the virus that infected mink must be further studied and evaluated.

How a harmless virus became dangerous
Waterfowl have long played host to influenza viruses, but these early strains were low in pathogenicity, said Wolfgang Fiedler, an ornithologist at the Max Planck Institute of Animal Behavior. The viruses weren’t too contagious or damaging.

But when these viruses that were harmless to wild birds spread to factory poultry farms ? where thousands of animals were crammed tight ? the disease spread rapidly and the virus could mutate, Fiedler explained.

The result was the highly contagious virus strains H5N1 and H5N8, which likely originated on poultry farms in East Asia, according to the Scientific Task Force on Avian Influenza and Wild Birds established by the UN.

Farmed ducks likely become infected from wild birds. Ducks are “kept together with pigs, for example,” which aided the mutation process, noted Fiedler. Such animal husbandry methods “make a virus like this insanely happy.”

In fact, outbreaks of these highly pathogenic strains are typically associated with “intensive domestic poultry production and associated trade and marketing systems … via contaminated poultry, poultry products and inanimate objects,” according to the UN’s bird flu task force.

The highly contagious H5N1 and H5N8 virus strains were in turn transmitted to wild birds via infected farmed birds, explained virologist Timm Harder. The viruses could then be transmitted over great distances during bird migrations.

How much damage has the bird flu outbreak caused?
The ongoing avian flu outbreak is considered the largest observed in Europe to date, according to the European Food Safety Authority, an EU agency.

Between October 2021 and September 2022, 50 million farm birds had to be culled in 37 countries.

More than 3,800 highly pathogenic bird flu cases were counted in wild birds. Experts believe the number of unreported cases is probably much higher.

Until recently, bird flu mainly occurred in fall and winter.

“Now the virus is also circulating in wild birds during the summer months,” confirmed Harder, noting that the animals breed closely in large colonies in the warmer months, providing ideal conditions for the spread of the virus.

The avian influenza wave also reached South America for the first time in the fall. Peru, Venezuela, Ecuador and Colombia were among the countries affected. In Honduras, more than 240 dead pelicans were found in one week alone.

Harder said he is concerned that the virus could spread from South America to Antarctica and endanger penguin populations. Apart from Antarctica, only Australia has escaped the virus.

Despite the acute outbreak among birds, Harder sees one ray of hope in that the broad spread of the virus could promote immunity in wild birds. Antibodies have already been found in live animals.

Risk to humans from H5N1 bird flu remains low but we must prepare - WHO [Reuters.com, 9 Feb 2023]

By Jennifer Rigby and Gabrielle Tetrault-Farber

LONDON, Feb 8 (Reuters) - The recent spread to mammals of H5N1 influenza - commonly known as bird flu - needs to be monitored, but the risk to humans remains low, the World Health Organization said on Wednesday.

H5N1 has spread among poultry and wild birds for 25 years, Director-General Tedros Adhanom Ghebreyesus told reporters in a virtual briefing, but the recent reports of infections in mink, otters and sealions "need to be monitored closely".

He said the risk to humans remained low, noting that human cases have been rare since the flu strain emerged in 1996.

"But we cannot assume that will remain the case and we must prepare for any change in the status quo," Tedros said.

He said people were advised not to touch dead or sick wild animals and to instead report them to local and national authorities, who were monitoring the situation.

The WHO also recommended strengthening surveillance in settings where humans and animals interact, he said.

"WHO is also continuing to engage with manufacturers to make sure that, if needed, supplies of vaccines and antivirals would be available for global use," he said.

WHO Warns Bird Flu Could Jump to Humans [Gizmodo, 9 Feb 2023]

By Lauren Leffer

Avian influenza has recently been recorded spreading among minks and other mammals. The World Health Organization has now acknowledged that could be very bad.

The World Health Organization has issued an ominous warning about bird flu. In a Wednesday press briefing, the international agency’s director-general, Tedros Adhanom Ghebreyesus, noted that the disease’s current trajectory leaves humans worryingly exposed.

Over the past year, avian influenza has gone viral, worldwide?obviously in a bad way. Outbreak after outbreak of a particularly dangerous strain of H5N1 bird flu has popped up in both wild and domestic birds on every continent aside from Antarctica (and scientists are becoming increasingly worried about the penguins there too.) Now, even mammals appear to be falling victim to the disease.

“H5N1 has spread widely in wild birds and poultry for 25 years, but the recent spillover to mammals needs to be monitored closely,” WHO’s Ghebreysus said. “Since H5N1 first emerged in 1996 we have only seen rare and non-sustained transmission of H5N1 to and between humans. But we cannot assume that will remain the case, and we must prepare for any change in the status quo,” he added.

Usually, H5N1 only spreads between birds. But in this ongoing series of outbreaks, something unsettling has started to happen. Mammals are getting sick too. In test results announced last month, three grizzly bears in Montana tested positive for bird flu. Similar cases have been noted among otters and foxes in the United Kingdom. Earlier this week, Peruvian officials confirmedthat they’d detected the viral strain among multiple sea lions and at least one dolphin in the South American country.

Most disconcertingly: in an outbreak among minks on a Spanish fur farm, H5N1 appeared to spread from weasel to weasel. In other instances of mammalian infection, the assumption is that mammals pick up avian influenza through direct contact with wild, infected birds. With the (now culled) minks though, science suggests that wasn’t the case.

A report about the incident published in October 2022 concluded that the number of infected animals and the way the spread occurred “indicate that an onward transmission of the virus to other minks may have taken place.” The report researchers also noted that the viral strain found among the farmed weasels carried mutations, some of which could potentially make the disease more transmissible between a wider array of species?though more conclusive studies on this are ongoing.

Minks have very similar respiratory tracts to humans. Among animals, they’re considered a likely vector point for new and emerging diseases. Already, we’ve seen this play out with covid-19. One 2021 study concluded that that the weasels could be a “highly susceptible host species,” of avian influenza, specifically.

In the past year, there’s been one documented case of the virus infecting a person in the U.S., along with at least one case in China. In total, the current spreading H5N1 variant has led to fewer than 10 known cases in people since December 2021. Further, there’s been no evidence of any human-to-human transmission in this current set of outbreaks, according to WHO and the Centers for Disease Control. Though human-to-human transmission is possible, the phenomenon has rarely occurred since the disease first emerged in people in 2003. H5N1 has never before been documented passing among humans in any sustained way.

For those reasons, Ghebreyesus qualified his remarks and noted that “For the moment, WHO assesses the risk to humans as low.” But without enough attention and action?there’s no guarantee things stay that way.

WHO says it is working with international governments to carefully keep tabs on the situation. And the agency recommends that countries boost their own internal surveillance programs as well?particularly where humans and animals commonly interact.

The agency also had a guidance for individual humans. “As always, people are advised not to touch or collect dead or sick wild animals, but to report them to the local authorities,” Ghebreyesus said. If you want to avoid becoming patient zero for the next global pandemic, Gizmodo suggests you follow that advice.

Bird Flu Isn’t a Danger to Humans...Yet [TIME, 9 Feb 2023]

BY HALEY WEISS

Avian Flu is Far From Becoming a Human Pandemic | Time

Bird flu appears to be on the move. A particularly nasty strain of the H5N1 virus is currently causing the worst outbreak of the disease among birds since it was first identified in China in 1996. Europe is deep into its second commercial season of widespread contagion, and the U.S. is seeing its deadliest 12-month period for poultry in recorded history, with 58 million animalsaffected so far. Records are also being broken in Japan, where a plan to cull 10 million poultry was announced in mid-January amid the appearance of a different but similar subtype, H5N2.

The past few years have taught us all how quickly a virus can spread, and avian influenza is no exception. Already, the current strain has affected a wider geographic area and more species than any other bird flu in the last two decades. Though it’s still too early for experts to say exactly why this is, the unique features of this outbreak (and what we do know about avian flu as a category of viruses), can get us a bit closer to understanding what might come next.
Is avian flu going to be the next human pandemic?

According to experts, the current form of avian flu spreading among poultry is unlikely to significantly impact human populations. For as long as the virus has been around, there have been cases of infection in humans, of which over 50% have been fatal. But overall cases have been fairly rare.

This is primarily due to the way that flu viruses bind to cells during the process of infection. The receptors that they exploit on the outside of cells look a bit different in every vertebrate class, and viruses tend to play favorites, evolving to stick to certain creatures’ cells more effectively than others. For H5N1, the target is birds. Still, “just because it has an avian-receptor binding preference does not mean that it cannot bind at all to human cells,” says Samantha Lycett, a University of Edinburgh researcher who studies how disease evolves and spreads. “It just doesn’t do it very well.” In fact, it does it so poorly that there are only a handful of recorded instances of H5N1 being spread from one human to another?and a virus can’t pose a real pandemic risk unless it’s great at that.

As we’ve seen with SARS-CoV-2, however, viruses can evolve to sidestep biological obstacles.

If H5N1 mutates into a strain better suited to attack human cells, we could be in trouble. H5N1 has already been found in other mammalian species, including foxes, bears, and most concerningly, in an outbreak at a Spanish mink farm in October. “The thing that was different about the mink farm was that it was clearly spreading from mink to mink,” says Paul Digard, chair of virology at the University of Edinburgh. “That that variant of it was a mammalian-transmissible virus makes it intrinsically more worrying.” It’s unclear how exactly the minks contracted the virus in the first place, but after numerous infected wild birds were found in the surrounding area, experts have suggested that excrement or remains from the wild birds could have somehow been tracked into the farm.

Why the current bird flu has spread so far, so fast
Even among birds, the current H5N1 strain also seems to be more infectious than past iterations. Most wild birds are generally less susceptible to infection than domestic poultry, primarily because more dramatic cellular differences across the many species of birds out in nature make it harder for the virus to be equally effective everywhere. But the recent outbreaks have spread to more unusual bird species, explains Lycett, including those who may be responsible for carrying the virus to new areas. In Scotland, where she and Digard live, there’s been a record number of deaths among seabirds. “We’ve lost a substantial fraction of the world population of things like gannets and skewers,” says Digard. “It’s a bit too soon to say whether they’ll bounce back or not.” Seabirds generally don’t catch avian flus, and the distances they travel have been a main cause of the recent spread.

“Seabirds have a slightly different mix of flu subtypes than do other migrating wildlife. So it’s kind of unusual, because they normally seem to have their own separate circulation,” Lycett says. As far as animals go, wild birds make for a nearly impossible-to-track disease vector, as they move around before researchers can formally count the infected. Even rats needed help from ships to spread the plague.

Without better understanding the current strain of the virus, it’s hard for experts to say exactly why this one is so much more virulent or how likely it is that mutations that make it more of a threat to mammals will occur in the future. In the meantime, the burden of the outbreak in the U.S. is being shouldered by farmers who keep commercial poultry, more of whom have had to kill off their flocks this year than ever before?and consumers who have had to pay high prices for eggs over the past few months.

“It is devastating to see these animals dying,” says Gino Lorenzoni, assistant professor of poultry science and avian health at Penn State. “Especially to the people that work with poultry.

I mean, they get attached to their flocks. It’s devastating, emotionally and also economically.”

Should you worry about bird flu right now?
Across the U.S., some 58 million birds have died or had to be killed because of infection. These nationwide depopulations are one of the main reasons that eggs are so expensive right now?a shortage of laying hens means a shortage of eggs.

The good news: Aside from the damage they’ll cause to your wallet, there are no other dangers to eating eggs and poultry right now, especially if they’re well-cooked. In the past, when humans have occasionally caught avian flu, none have been infected by consuming eggs or poultry products. There are also good failsafe measures in place to prevent sick birds from entering the production line in the first place. When a chicken has avian flu, it’s not that hard to tell. The incubation period is relatively short, and when they get sick, they get really sick, and can even drop dead, seemingly out of nowhere. The U.S. Department of Agriculture also keeps a complete and public record of all reported detections of disease in commercial flocks, and people who work regularly with poultry have long lists of protocols and protective measures that they’re already used to?for them, the threat is currently larger, but not new.

For the rest of us, the main priority for the time being should be to “treat the virus with respect,” as Lorenzoni puts it. If you keep one or two chickens in your backyard, that means keeping them where wild animals can’t touch them and making extra sure to wear full protective gear like goggles, Tyvek suits, and most importantly, shoe coverings that eliminate the risk of tracking potentially virus-ridden bird poop inside any enclosure. If you have pets, this means keeping a close eye on them when they’re outside the home, and preventing them from picking up any bird carcasses or excrement that may be laying around. And if a seagull tries to steal your sandwich, maybe let him have it this time.

Bird flu infects Colorado mountain lion, black bear and skunk, all now dead [The Denver Post, 9 Feb 2023]

By CONRAD SWANSON

The highly pathogenic avian influenza has killed thousands of wild birds and has now infected more Colorado wildlife

Three animals in Colorado, each of them now dead, tested positive for the highly pathogenic avian influenza that’s sweeping across the country, state wildlife officials said in a release.

The H5N1 variant of the bird flu is ravaging bird populations across the world. Mammals, including humans, can also catch it.

State Parks and Wildlife officials first confirmed this strain of the bird flu among wild geese in northeast Colorado last March, agency spokesman Travis Duncan said in a release. Now they’ve confirmed three cases of the virus in mammals, which showed signs of neurologic symptoms, general weakness and organ damage before their deaths.

First came a black bear in Huerfano County, which state wildlife officials euthanized after seeing it suffer from seizures, Duncan said. The animal’s remains froze in the wild until it thawed enough to be taken to a health lab for testing, which confirmed traces of H5N1.

Then, a skunk from Weld County tested positive for the virus in November, Duncan said.

And finally, in mid-January, a mountain lion was found dead in Gunnison County, Duncan said. The lion also tested positive for H5N1 and suffered liver damage and bronchointerstitial pneumonia.

“Similar to many local species, mountain lions move through our communities on a regular basis as they travel between seasonal ranges throughout the year,” Brandon Diamond, a Parks and Wildlife manager, said in the release. “It was only a matter of time before the first (bird flu) case was confirmed in Gunnison County based on known cases in adjacent counties.”

Other cases of the virus in Colorado mammals await testing confirmation, Duncan said.

Mammals typically contract the virus after feeding on infected birds.

Humans should avoid contact with sick or dead birds, Duncan added.

Fewer than 10 human cases have been reported since December 2021 and human-to-human transmission has not been documented, according to the U.S. Center for Disease Control and Prevention. The disease is rare among humans, with fewer than 1,000 cases documented since 1997, but the virus can carry a fatality rate of about 50%.

Bird flu: Don't assume risk to humans will remain low, WHO warns [Sky News, 9 Feb 2023]

The World Health Organisation says reports of bird flu in mink, otters and sealions "need to be monitored closely" and we must prepare for a change in the risk level to humans.

The risk of bird flu spreading in humans is low at the moment - but it doesn't mean it will necessarily stay that way, the World Health Organisation (WHO) has warned.

H5N1 influenza - commonly known as bird flu - has cropped up in mammals around the world, from grizzly bears to dolphins and domestic cats.

Last week it was confirmed bird flu has spilled to mammals in the UK, with otters and foxes testing positive for the virus.

WHO director-general Dr Tedros Adhanom Ghebreyesus said in a briefing that the recent reports of infections in mink, otters and sealions "need to be monitored closely".

He said the risk to humans remained low, noting that human cases have been rare since the flu strain emerged in 1996.

"But we cannot assume that will remain the case and we must prepare for any change in the status quo," Dr Tedros said.

The current outbreak started in October 2021, sweeping through poultry farms and wild birds.

The virus is highly infectious and causes rapid illness and death in birds.

Whole flocks have to be culled to try to curb the spread, with the number of dead birds now in the millions.

Since the outbreak started there have been five cases of H5N1 in humans worldwide, including one in the UK and one death in China.

In the last 20 years, there have been 868 cases and 457 deaths, according to the WHO.

In October last year, mink started dying of bird flu at a farm in Spain.

They weren't the first mammals to contract the virus, but the cases differed this time as it appeared to be spreading between the animals, from pen to pen.

In most instances 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.

Dr Tedros said people were advised not to touch dead or sick wild animals and to instead report them to local and national authorities, who were monitoring the situation.

The WHO also called on countries to strengthen surveillance in settings where humans and animals interact.

"WHO is also continuing to engage with manufacturers to make sure that, if needed, supplies of vaccines and antivirals would be available for global use," he said.

U.S. to test shots against bird flu outbreak, as Biden administration weighs poultry vaccinations [CBS News, 9 Feb 2023]

BY ALEXANDER TIN

Federal scientists are gearing up to test the first vaccines in poultry against bird flu in years, as Biden administration officials say they have now begun weighing an unprecedented shift in the U.S. strategy to counter the growing outbreak.

The move comes amid mounting concern over the threat posed by the ongoing spread of highly pathogenic avian influenza over the past few years, which has devastated flocks of wild and commercial birds around the continent.

A record 58 million birds ? mostly commercially-raised poultry ? have died in the outbreak so far, according to figures tallied by the USDA's Animal and Plant Health Inspection Service ? either killed by the virus itself or put down in efforts to quash its transmission. Every state has detected the virus spreading among wild birds and 47 have spotted them in poultry.

"The decision to proceed with vaccination is complex, and many factors must be considered before implementing a vaccination strategy," USDA spokesperson Mike Stepien said in a statement, adding that the inspection service is discussing the options and "soliciting input from many different industry stakeholders that would be impacted."

While the Biden administration has so far not greenlighted the use of vaccines for highly pathogenic avian influenza, several shots had been licensed for potential use in previous outbreaks. Poultry are already regularly vaccinated for other diseases, like infectious bronchitis.

While animal vaccines can take years to be licensed, Stepien said some parts of the process can be accelerated for emergencies.

It is not yet clear whether vaccines are available that will work against clade 2.3.4.4b, the strain behind the current outbreak in the U.S.

"There are a lot of moving parts to this kind of testing. And some of it is just pure logistics of getting everything in place to do the testing, getting the vaccines that are updated, getting things from parties that are involved, different manufacturers," said Erin Spackman, a virologist who studies avian influenza vaccines at the USDA.

While it is not always a requirement for animal shots to be licensed by the department, the trials will offer an early independent evaluation of how well a vaccine works in this case.

Antibody studies suggest earlier vaccines might not be as well-matched against the strain now driving the current outbreak, prompting the need for tests.

"On the test, it's a twofold reduction, but that makes it sound a lot closer related than it is. In vaccine-speak, it means it's starting to drift away," said Spackman.

Spackman said evaluating the vaccines can take three months, from when birds get their shot ? often in the back of the neck or thigh ? to studying their response to the virus after immunity develops.

Vaccine makers say they are also closely tracking deliberations by the U.S. and other countries over the possibility of poultry vaccination, as well as assessing their own shots.

A spokesperson for Merck Animal Health said the company has an "extensive, ongoing research program" developing vaccines that can work with so-called Differentiating Infected from Vaccinated or DIVA strategies ? an approach that involves systematically hunting for the virus among vaccinated flocks, in hopes of preventing undetected spread among immunized birds.

When to vaccinate poultry?
Officials have so far been wary of deploying vaccines against the outbreak, citing concerns that the use of the shots could make it harder to export American poultry products.

"What is the trigger point of when you might use vaccination? And that's what they're looking at. Is it so many birds in a poultry farms in an area getting infected? Or is it a certain amount of economic loss? Or is it because a neighboring state has the virus in poultry, and you're concerned? So there's those are really the tough, tough questions," said poultry veterinarian David Swayne.

Before retiring to become a consultant, Swayne served for nearly three decades in the USDA's infectious disease arm and was the director of the department's top research facility for dangerous pathogens.

Swayne noted there are several high-income countries in Europe that are "further along" in exploring DIVA strategies that would work with poultry exports, after wrestling for years with their outbreak. Others, including Indonesia and China, have already rolled out poultry vaccinations for bird flu.

Under one approach, birds who die of any cause in a vaccinated flock could be aggressively tested for the virus, Swayne said, or live birds might be systematically sampled for antibodies in their blood through a more complex process. Surveillance may also be possible through swabbing the environment, like checking the containers birds drink water from.

"We want to make sure our partners understand that, if we use them, we're going to use them in the right the right manner so that they can feel secure and safe that the products they buy are not products that might contain, say, a highly pathogenic avian influenza virus," said Swayne.

Authorities would also need a way to coordinate tracking viruses for updates to the vaccines, potentially similar to how the World Health Organization issues recommendations for manufacturers of human flu shots to keep pace with the latest strains.

However, Swayne cautioned that poultry producers will still need to take steps to shield their flocks from contact with wild birds and other ways the virus could spread.

Like their counterparts abroad, American wildlife officials have spotted the virus decimating groups of birds across a range of species. Officials believe the virus is largely being transmitted to commercial poultry flocks by wild birds migrating across the Americas.

"Biosecurity really is the first line of defense, and any vaccination that might be done is only sort of another layer of protection, sort of an insurance policy," he said.

Is it a threat to humans?
Authorities say the risk the virus poses to humans seems to be low for now, despite a 56% fatality rateamong the handful of people who have tested positiveafter direct contact with infected birds.

Out of more than 6,000 poultry workers that American health authorities have tracked after exposure to infected birds, only one has tested positive for the virus.

Regardless, officials have urged Americans to avoid handling dead or sick birds to reduce their risk. The virus has spilled over from birds to other species, often from coming into contact with the carcasses of infected birds.

"Somewhat concerning is that there's been transmission to mammals in a variety of terrestrial mammals, which are basically the most of them are predatory mammals," the Centers for Disease Control and Prevention's Tim Uyeki told a webinar hosted by Emory University last month.

The federal Administration for Strategic Preparedness and Response also already maintains a program with vaccinemakers to "make and test small quantities" of shots for humans that can be ramped up to large-scale production if needed.

"High on my radar. We've already been in touch with our teams as to where we are with both surveillance and detection, as well as our USDA colleagues on the detection in the avian population as well," CDC Director Dr. Rochelle Walensky told a panel of the agency's advisers this week.

The spillover of bird flu to mammals must be ‘monitored closely,’ WHO officials warn: ‘We need to be ready to face outbreaks in humans’ [Fortune, 9 Feb 2023]

BY ERIN PRATER

Cases of HN51 bird flu in mammals like those reported recently must be “monitored closely,” the head of the World Health Organization said Wednesday, as the organization’s experts called on public health officials to prepare for human outbreaks of the disease.

H5N1 avian flu has existed for a quarter century. Only rarely have human cases occurred, with no sustained transmission reported. But “we cannot assume that will remain the case,” WHO Director General Tedros Adhanom Ghebreyesus said at a news conference. New, frequent reports that the disease has crossed into small mammals like minks, otters, foxes, and sea lions are cause for alarm, given the species’ similarities with humans, he noted.

While the risk to people remains low, public health officials must prepare “to face outbreaks in humans, and be ready also to control them as soon as possible,” Dr. Sylvie Briand, director of Global Infectious Hazard Preparedness and Emergency Preparedness at the WHO, told Fortune.

Ghebreyesus cautioned against touching or collecting sick or dead animals, and encouraged those who encounter such to report them to local authorities. Countries must strengthen their avian flu surveillance in areas where humans and wild animals interact, he insisted. And public health officials must work with manufacturers to ensure that vaccines and antivirals are available for global use, he said.

‘Only the tip of the iceberg’
Tests on several sea lions and a dolphin found dead in Peru in November have returned positive for the concerning strain of bird flu, Peruvian veterinary authorities said Tuesday, the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota reported. At least 585 sea lions and 55,000 birds have been found dead in the country, their deaths likely due to H5N1, a federal agency reported Monday.

What’s more, a lion held in a Peruvian zoo recently died of the virus, CIDRAP recently reported, citing media reports. Foxes, dolphins, opossums, skunks, raccoons, and other types of bears are among other species that have been infected since last year, according to the U.S. Department of Agriculture. A “mass mortality event” among seals on Russia’s Caspian Sea coast in December was caused by avian flu, though the strain was not named, CIDRAP recently reported, citing Dagestan State University.

In late January, 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. And surviving infected harbor and gray seals identified in New England last summer by a team led by Jonathan Runstadler, professor and chair of the Department of Infectious Disease and Global Health at Tufts University’s Cummings School of Veterinary Medicine, were unable to orient themselves and swim properly, he told the Journal of the American Medical Association in a recent article.

These instances are just a few of numerous recent reports of outbreaks among mammals, including at a worrying outbreak at a mink farm in Spain. It’s trend that should worry public health officials, Mike Ryan, executive director of the WHO’s health emergencies program, told Fortune on Wednesday.

“Small mammals may not look like us,” but they share many physical similarities with humans, he said.

The H5N1 virus could win the lottery, so to speak, by quickly and ably adapting to humans and starting an epidemic somewhere?then, possibly, a pandemic. Most viruses don’t get that lucky. But the more opportunity the virus has to spread, the better the chance that it will succeed, Ryan added.

While there have been identified instances of H5N1 in mammals since the virus was first detected in the late 1990s, never have there been so many, Dr. Jay Varma, chief medical adviser at the New York-based think tank Kroll Institute, told Fortune.

Recently discovered H5N1 mass fatality events among mammals “are probably only the tip of the iceberg,” he cautioned.

“We only know about these events when there are very large die-offs that are recognized by people and somebody actually does the testing and reports the results,” he said. “There may be smaller die-offs, larger die-offs, people afraid that no one will buy their chickens if they report a die-off. We know there are many instances where lab testing isn’t done.”

Worst outbreak in U.S. history for birds
The H5N1 strain of avian flu has been responsible for the deaths of tens of millions of birds in the U.S. in recent months, and countless millions worldwide. The strain?first identified in domestic waterfowl in China in 1996?is behind more than 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,” Rajiv Chowdhury, senior epidemiologist and professor of global health at Florida International University, recently told Fortune.

Trend of ‘low’ risk to humans may not hold
Economic and food-supply issues aside, the strain poses a threat to humans because it can severely sicken them, though it has only done so in relatively small numbers so far. Hundreds of human cases were identified in Egypt earlier this century, though there were no confirmed reports of sustained human-to-human transmission.

But that trend may not hold, experts warn. In January the WHO reported that a previously healthy Ecuadorian girl had been hospitalized with the virus, and was under sedation and on a ventilator. Just how she contracted the virus was uncertain and under investigation, but poultry her family had recently purchased died without apparent cause.

The world appears to have dodged a proverbial bullet, with the girl’s condition improving and no additional human cases reported since, WHO officials said Wednesday. They also confirmed that the girl contracted the virus from poultry, not from another human.

The likelihood of human-to-human transmission of H5N1 is “very low,” Chowdhury recently told Fortune. 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 said, signifying the start of a “new global influenza pandemic.”

The risk for sustained transmission among humans could be anything from one in 10 to one in 100,000, Varma said, adding that the uncertainty necessitates the conveyance of a mixed risk message. The average person shouldn’t be alarmed by H5N1 at the moment. But governments must take actions like “investing more heavily in programs that detect and characterize these viruses,” in addition to funding lab testing among animals.

Governments must also ensure there’s a safe and effective vaccine ready to go for humans, and that supplies are adequate. If a vaccine were developed and approved for animals like chickens, turkeys, and pigs, it could reduce spread among livestock, as well as the risk of spillover to humans who work with them, he added.

“We know from COVID that you can’t just vaccinate your own country,” Varma said.

“Everywhere around the world needs to be protected. There needs to be more investment in this.”

The Spanish Flu as a cautionary tale
The 1918 flu pandemic serves as a cautionary tale as the world faces a potential H5N1 pandemic, Chowdhury said. Like the H5N1 flu, the Spanish Flu is thought to have avian origins.

And 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.

When H5N1 infects humans, the inflammation it causes can lead to lung cells becoming “intensely inflamed”?to an extent not 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, 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.

Because the virus hasn’t crossed over to humans in a sustained manner, it’s uncertain what an easily transmissible human version of H5N1 might look like, Varma said. “But we can guess, based on prior flu epidemics, that it would be very deadly to humans.”

COVID has been “somewhat manageable” because younger individuals are typically less likely to suffer severe disease, he said. The same was not true of the Spanish Flu, which killed more young than old. If human-to-human transmission of H5N1 begins to occur, “we shouldn’t automatically assume that young people or even children will be better protected,” he said. “They may very well be at higher risk.”

New zoonotic diseases, or diseases that transmit from animals to people, tend to result in high mortality rates among the people they infect. They’re not well adapted to humans and tend to cause copious amounts of damage in the lungs, though they’re not usually very transmissible, Briand said.

Once such viruses adapt to human transmission?if they do?the fatality rate may drop. While the Spanish Flu killed a whopping 50 million?around seven times greater than COVID’s official global death toll of just under 7 million?it killed no more than 4% of those it infected, according to Briand?a fatality rate much lower than that of H5N1 in birds.

“In 1918, we didn’t have antibiotics,” she said. “We didn’t have antivirals either. We didn’t have vaccines. And we didn’t have any of the tools we have now to control flu outbreaks. We’re in a much better place, of course, now than we were a century ago.”

While the risks to humans posed by H5N1 are weighty, they can be mitigated, Ryan emphasized.

The point is “not to be scared of viruses,” he said, adding that “they’re out there and always will be.”

“We need to focus on our game plan, what we need to do to make sure we keep everybody safe,” he said. “Don’t just spend time thinking of the risk. Act upon those risks and they can be significantly reduced, in terms of impact.”

The spillover of bird flu to mammals must be ‘monitored closely,’ WHO officials warn: ‘We need to be ready to face outbreaks in humans’ [Yahoo Finance, 9 Feb 2023]

By Erin Prater

Cases of HN51 bird flu in mammals like those reported recently must be "monitored closely," the head of the World Health Organization said Wednesday, as its experts called on public health officials to prepare for human outbreaks of the disease.

H5N1 avian flu has existed for a quarter century, WHO Director General Tedros Adhanom Ghebreyesus said at a news conference. But new, frequent reports that the disease has crossed into small mammals like minks, otters, foxes, and sea lions are cause for alarm, given the species' similarities with people.

While the risk to people remains low, according to Ghebreyesus, public health officials must prepare "to face outbreaks in humans, and be ready also to control them as soon as possible, so the virus doesn't spread any farther," Dr. Sylvie Briand, director of Global Infectious Hazard Preparedness and Emergency Preparedness at the WHO, said.

Since H5N1 was identified nearly three decades ago, only rarely have human cases occurred, and there has been no sustained transmission among them, Ghebreyesus said. But he added: "We cannot assume that will remain the case. We must prepare for any change in the status quo."

He cautioned people against touching or collecting sick or dead animals, and encouraged them to report the incidences to local authorities.

Countries must strengthen their avian flu surveillance in areas where humans and wild animals interact, Ghebreyesus insisted. And public health officials must work with manufacturers to ensure that vaccines and antivirals are available for global use, he said.

A growing mammalian outbreak
Tests on several sea lions and a dolphin found dead in Peru in November have returned positive for the concerning strain of bird flu, Peruvian veterinary authorities said Tuesday, the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota reported. At least 585 sea lions and 55,000 birds have been found dead in the country, their deaths likely due to H5N1, a federal agency reported Monday.

What's more, a lion held in a Peruvian zoo recently died of the virus, CIDRAP recently reported, citing media reports.

The cases join other recent similar reports of bird flu outbreaks among mammals, especially small mammals?including at a mink farm in Spain. A "mass mortality event" among seals on Russia's Caspian Sea coast in December was caused by avian flu, though the strain was not named, CIDRAP recently reported, citing the country's Dagestan State University.

It's trend that should worry public health officials, Mike Ryan, executive director of the WHO's health emergencies program, told Fortune on Wednesday.

"Small mammals may not look like us," but they share many physical similarities with humans, he said. "That's why drugs are tested on animals."

"The more a virus circulates in animals, the higher the risk for humans as well," Briand told Fortune on Wednesday.

The H5N1 virus could win the lottery, so to speak, by quickly and ably adapting to humans and starting an epidemic somewhere?then, possibly, a pandemic. Most viruses don't get that lucky. But the more opportunity the virus has to spread, the better the chance that it won't hit a dead end and fizzle out, Ryan said.

While there have been identified instances of H5N1 in mammals since the virus was first detected, never have there been this many, Dr. Jay Varma, chief medical adviser at the New York-based think tank Kroll Institute, told Fortune, adding that the recent known H5N1 mass-die-off events among mammals "are probably only the tip of the iceberg."

"We only know about these events when there are very large die-offs that are recognized by people and somebody actually does the testing and reports the results," he said. "There may be smaller die-offs, larger die-offs, people afraid that no one will buy their chickens if they report a die-off or something. We know there are many instances where lab testing isn't done."

Worst outbreak in U.S. history for birds
The H5N1 strain of avian flu has been responsible for the deaths of tens of millions of birds in the U.S. in recent months, and countless others worldwide. 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,” Rajiv Chowdhury, senior epidemiologist and professor of global health at Florida International University, recently told Fortune.

Dangerous for people, too
Economic and food-supply issues aside, the strain poses a threat to humans because it can sicken them, though it has only done so in relatively small numbers so far. Hundreds of human cases were identified in Egypt earlier this century, though there was no sustained human-to-human transmission.

But the trend of minimal transmission among humans may not hold, experts warn. The WHO reported in January that a previously healthy Ecuadorian girl had been hospitalized with the virus and was under sedation and on a ventilator as of Jan. 17. Just how she contracted the virus was uncertain and under investigation, but poultry her family had recently purchased died without apparent cause.

The world appears to have dodged a proverbial bullet, with the girl's condition improving and no additional human cases reported sense, WHO officials said Wednesday. They also confirmed that the girl contracted the virus from poultry, not from another human.

The likelihood of human-to-human transmission of H5N1 is “very low,” Chowdhury said. 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.”

The risk for sustained transmission among humans could be anything from one in 10 to one in 100,000, Varma said, adding that the uncertainty necessitates the conveyance of a mixed risk message. The average person shouldn't be alarmed by H5N1 at the moment. But governments must take actions like "investing more heavily in programs that detect and characterize these viruses," in addition to funding lab testing among animals, in preparation for a potential pandemic.

Governments must also do what they can to ensure there's a safe and effective vaccine ready to go for humans, and that supplies are adequate. If a vaccine were developed and approved for animals like chickens, turkeys, and pigs, it could reduce spread among livestock, as well as the risk of spillover to humans who work with them, he added.

"We know from COVID that you can't just vaccinate your own country," he said. "Everywhere around the world needs to be protected. There needs to be more investment in this."

The Spanish Flu as a cautionary tale
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 virus hasn't crossed over to humans in a sustained manner, so it's uncertain what an easily transmissible human version of H5N1 might look like, Varma said. "But we can guess, based on prior flu epidemics, that it would be very deadly to humans."

COVID has been "somewhat manageable" because younger individuals are typically less likely to suffer severe disease, he said. The same was not true of the Spanish Flu, which killed more young than old?"which is pretty terrifying, if you think about it."

If human-to-human transmission of H5N1 begins to occur, "we shouldn't automatically assume that young people or even children will be better protected," he said. "They may very well be at higher risk."

New zoonotic diseases, or diseases that transmit from animals to people, tend to result in high mortality among those they infect. They're not well adapted to humans and tend to do copious amounts of damage in the lungs, Briand said.

"When you look at the case fatality rate, we're scared because it's quite higher, 30% to 50%, but those viruses are not very transmissible," she added.

Once such viruses adapt to human transmission?if they do?the fatality rate may drop. While the Spanish Flu killed a whopping 50 million?around seven times greater than COVID's official global death toll of just under 7 million?it killed no more than 4% of those it infected, according to Briand.

"In 1918, we didn't have antibiotics," she said. "We didn't have antivirals either. We didn't have vaccines. And we didn't have any of the tools we have now to control flu outbreaks. We're in a much better place, of course, now than we were a century ago."

While the risks to humans posed by H5N1 are real and substantial, they can be mitigated, Ryan said.

The point is "not to be scared of viruses," he said, adding that "they're out there and always will be."

"We need to focus on our game plan, what we need to do to make sure we keep everybody safe. Don't just spend time thinking of the risk. Act upon those risks and they can be significantly reduced, in terms of impact."

This story was originally featured on Fortune.com