Influenza A virus subtype H5N1

Can You Get Bird Flu?:-

Maybe you’ve noticed: Eggs are really expensive.

By late last year, the average cost of a dozen Grade A large eggs had more than doubled since January. They’ve been so pricey — more than $10 at certain retailers — that some people are now smuggling them into the US from Mexico.

One major culprit? The spread of avian influenza, a.K.A. Bird flu.

The viral disease has wiped out tens of millions of wild and farmed birds in the US, including egg-laying hens, many of which were not infected but were culled to stop the flu from spreading. The ongoing surge is now considered the largest avian influenza outbreak in US history.

 A grocery worker stocks shelves with eggs in Detroit, Michigan, on January 18. Matthew Hatcher/Bloomberg via Getty Images

There’s some comfort in the name, avian influenza. The virus that’s been tearing through poultry farms, known as H5N1, typically targets birds, not humans.

But a recent outbreak of H5N1 at a mink fur farm in Spain has some scientists worried. Farms with dense populations of minks — which are mammals, like us — are ideal places for this virus to acquire new mutations or other genetic changes that could help it spread more easily between humans. And testing at the fur farm revealed the virus had already acquired at least one such mutation.

Meanwhile, wildlife monitoring has shown some other mammals have recently contracted bird flu, including a few grizzly bears in Montana, skunks, and otters.

This makes us wonder: Is bird flu creeping closer to humans?

The short answer: no. In its current form, H5N1 doesn’t have the machinery to easily infect humans or spread quickly among us. That’s the good news. What is concerning is that avian influenza viruses are known to change quickly — especially when they’re abundant and spreading among certain animal populations. Hence why some scientists are worried now.

“Avian influenza is near the top of the list in terms of viruses that have pandemic potential,” Daniel Olson, an epidemiologist at the University of Colorado, told Vox. “Coronaviruses are up there, too, but avian influenza is just as high — and maybe even higher.”

That doesn’t mean avian influenza is about to become the next pandemic. Yet experts are on alert, and are looking for any signs that the situation might change. Here’s what to know about the current human risk of bird flu.

What it would take for bird flu to become a human pandemic

The H5N1 virus that’s spreading now was first detected in the ’90s, at a goose farm in southern China, making it a relatively new type of avian influenza. (There are other strains of bird flu, but for the purposes of this article, we’ll use “bird flu” to mean H5N1.)

In the decades since, the virus has mostly been a problem for birds, especially domestic poultry. It’s highly contagious, and infection can cause severe damage to birds’ internal organs. Outbreaks of the virus can wipe out 90 percent or more of farm birds within 48 hours.

 Avian influenza infects wild birds like snow geese, pictured here. Jim Watson/AFP via Getty Images

A number of mammals including humans have also become infected over the years. While it can kill us — H5N1 has a frighteningly high mortality rate — this virus has yet to become widespread or approach anything close to a pandemic.

For any pathogen to have the potential to cause a human pandemic, it has to have three important qualities, according to several flu experts. It must spread easily among humans, particularly through the air. It must cause human disease. And it must be something that most of our immune systems haven’t encountered before — that is, it must be novel.

Thankfully, H5N1 doesn’t meet all of these criteria.

For one, it doesn’t have the right machinery to efficiently infect our bodies and isn’t easily transmitted between them.

To infiltrate a host, viruses first have to bind to certain receptors on the surface of their cells. The virus that’s currently spreading, H5N1, does this using a specific kind of protein known as hemagglutinin 5, or H5. You can think of H5 as a key and receptors as the locks.

Following this metaphor, H5 can unlock certain receptors found in cells that line the respiratory and digestive tracts of birds. By invading those cells and replicating, the virus can damage these vital systems, making it difficult for the birds to breathe and easy for them to spread the virus among themselves (through breath and feces).

Humans have some similar, avian-type receptors in our respiratory systems, too. But for reasons scientists don’t fully understand, they don’t make us as vulnerable to avian flu as birds are. Critically, we also have a higher number of different, non-avian-type receptor that bird flu viruses don’t like to bind to quite as much. The abundance of those non-avian receptors in our noses seems to protect us from being easily infected by viruses like H5N1.

The upshot: H5N1 doesn’t easily bind to cells in our airways, so it’s harder for the virus to infect us. Humans can still be infected, but likely only if we’re exposed to a large amount of virus or the conditions are just right for transmission (though scientists don’t know what those conditions are, exactly). Most people who have come down with bird flu spent a more-than-casual amount of time around birds, usually while working with or around sick flocks.

“If you look at all the H5 infections over the past two decades or more, the vast majority of those reported exposure to sick or dying poultry prior to the infection,” said Richard Webby, a virologist specializing in animal and bird influenza at St. Jude Children’s Research Hospital.

Flu viruses that can’t cause infection in humans’ airways are much harder to transmit among humans — and therefore, they can’t cause a pandemic. Unless something changes.

Bird flu evolves quickly. That’s what makes it a threat.

If there’s anything concerning about the current bird flu, it’s that it could mutate and evolve. If it’s not a threat to humans today, it could become one.

That’s because influenza viruses are incredibly changeable. Like other viruses, H5N1 picks up small mutations as it replicates within a host; over time, that can give the virus certain benefits (though mutations are often bad for the virus).

But influenza viruses can also undergo much bigger and more consequential shifts through a process called reassortment.

Reassortment is like something out of science fiction: When two influenza viruses infect the same cell in the same host, they can trade entire chunks of their genomes with each other, yielding a variety of Franken-flus.

That’s why it’s a red flag for researchers when avian flu spreads among animals that can also easily get sick with other kinds of influenza. Pigs, for example, have flu receptors in their respiratory systems that both human and bird viruses easily bind to, so they can get infected with both. Should these two viruses meet inside these animals, they might swap parts, producing an avian flu that can more easily infect mammals.

The same is true for mink: They can be infected by both avian and mammalian influenza. (The famous and particularly devastating 1918 pandemic likely originated in birds and may have passed through a mammal before jumping to humans.)

Experts fear that in “mixing vessels” like pigs or mink, H5N1 could exchange a segment of its genome that makes it easily transmissible among birds for one that makes it easily transmissible among mammals — and, eventually, to humans. In theory, that could lead to the creation of a virus with all of H5N1’s other bad personality traits — its ability to cause severe disease, for example — with the added advantage of, say, being able to easily infiltrate cells in our airways.

(There are some signs that the H5N1 virus that spread through the Spanish mink farm picked up a mutation that’s known to help it replicate more easily in mammals. It’s not clear, however, if the virus picked up the mutation before or after spreading to minks.)

 A mink at a fur farm in Denmark on November 14, 2020. Ole Jensen/Getty Images

These major genetic shifts are so worrying because they can produce novel viruses that humans have never been exposed to. Although our immune systems likely would be able to recognize and fight off a common strain of flu that’s mutated slightly over time, it’s much harder to mount a quick response to a brand new strain.

The potential to evolve novelty is what puts bird flu on the pandemic potential radar, according to Seema Lakdawala, a virologist and influenza A transmission specialist at Emory University. “Pandemics emerge with shifts,” she said.

Rest assured, not all genetic shifts produce a pathogen with pandemic potential, said Lakdawala. Plus, even if H5N1 does evolve a way to more easily invade our airways, that doesn’t guarantee it will be able to spread among humans. To be easily transmissible, the virus also needs to replicate efficiently once it’s inside the cell, and survive in the air after it’s expelled in a cough or a sneeze.

There’s little evidence that bird flu has adapted to spread easily between mammals, much less between humans. Emerging evidence suggests that in many H5N1 cases among wild animals — and in the latest mink farm cases — infections among multiple animals likely occurred not because of transmission between animals, but because several animals all ate infected birds loaded with virus.

The real public health risk of bird flu

There’s more good news: Even if bird flu does evolve tools to infiltrate a human host and spread among us, we have tools of our own to detect and combat the virus.

The US government already has a stockpile of human vaccines for bird flu, including those specifically for H5N1, according to the Centers for Disease Control and Prevention (CDC). There are also vaccines available for farm birds (though they’re not widely used, for reasons that Vox’s Kenny Torrella explains here).

Meanwhile, oseltamivir, a drug commonly used to treat more common types of flu infections, has been effective at treating human cases of H5 flu. And surveillance of flu in human and animal populations is a global health priority.

 A flock of turkeys at a farm in Conowingo, Maryland. Edwin Remsberg/VWPics/Universal Images Group via Getty Images

Bird flu does, however, pose an immediate threat to humans, not because we’re at risk of infection but because it’s squeezing the global food supply, according to Carol Cardona, an avian health expert at the University of Minnesota.

Eggs and other poultry products, as well as some wild birds, have long been relatively cheap and vital sources of protein in much of the world. Should avian influenza continue to rip through large farms, or spread to backyard coops, it could extend the cost-of-living crisis.

“The risk to humans is through food and food supply,” Cardona said. “And the people who are being cut off from food supply are at the lowest economic level.”

The US Department of Agriculture and the CDC monitor flu viruses found in both people and animals for signs of a novel virus with the potential to cause human disease — a critical component of pandemic preparedness, said Tim Uyeki, a medical epidemiologist and bird flu expert at the CDC. Although the disruptive virus freshest in our minds might be a coronavirus, most human respiratory pandemics in recent memory — those of 1918, 1957, 1968, and 2009 — have been caused by novel influenza A viruses.

“Constant vigilance and surveillance is needed worldwide to monitor the potential threat of these and other viruses as they evolve,” Uyeki said.

Changes to the environment like deforestation and a warming climate are also leading to more intermingling of different species and the infectious organisms that call them home — including flu. “We have humans and animals living closer together on a larger scale than we have in the past,” Olson said.

That intermingling could at some point create a flu with human pandemic potential, said Lakdawala. “The more attempts these viruses make right at jumping across these hurdles, the more likely they are that some of them may be successful,” she said. “Nature is so good at doing this.”

Or as Cardona put it: “Never bet against a flu virus.”

Peru Confirms H5N1 Avian Flu In Marine Mammals, Part Of Southward Spread:-

Veterinary authorities in Peru yesterday confirmed H5N1 avian influenza in sea lions and a dolphin, adding more reports of detections in mammals as the virus continues its push into Central and South America.

Peru's National Agrarian Health Service (SENASA) said surveillance for marine species on the country's coasts are part of its response to outbreaks in poultry. Tests on three sea lions found dead in November and one dolphin were positive for H5N1, SENASA said in a statement, which was translated and posted by Avian Flu Diary, an infectious disease news blog.

In a follow-up, SENASA said at least 585 sea lions and 55,000 wild birds have been found dead in seven of the country's coastal nature preserves, likely due to avian flu.

Also, media reports citing Peru's health ministry said tests on a zoo lion in central Peru identified H5N1 as the cause of death.

The reports add to a growing number of detections in mammals, including recent reports from the United Kingdom and H5N1 in farmed minks in Spain. The United States has so far reported 110 detections in mammal species. The H5N1 clade circulating in birds, poultry, and an increasing number of mammals has a mutation that makes the virus more recognizable by mammalian airway cells.

Seven human H5N1 infections have been reported, all involving people who had close contact with poultry. Some illnesses were mild, but some were severe or fatal. So far, no human-to-human transmission has been reported.

Poultry outbreaks surge in Central and South America

The World Organization for Animal Health (WOAH) last week raised concerns about not only the spread of the highly pathogenic avian flu to new countries in Central and South America, but also the speed of the spread over a 4-month period, with occasional spillovers to humans and mammals. The most recent human case was reported in a 9-year-old girl from Ecuador.

Newly affected countries include Bolivia, Colombia, Costa Rica, Ecuador, Honduras, Panama, Peru, and Venezuela. Chile reported its first high-path outbreaks in 20 years.

WOAH said outbreaks have already led to the loss of 1.2 million poultry in Central and South America, a concern given that poultry is one of the most consumed animal proteins in the region, with the fast-growing poultry sector providing income to thousands of families. It and the United Nations' Food and Agriculture Organization (FAO) recently created an expert group on avian flu, which met in December to make recommendations, which included stronger biosecurity and surveillance steps.

Outbreaks continue in other regions; WOAH notes mammal detections

In a separate report that covers global avian flu activity in the first 3 weeks of January, WOAH said there were 70 outbreaks in poultry during the period and 90 events involving other birds, mainly in Europe, but also in the Americas and Asia, affecting 3 million birds that died or were culled. Most of the activity involves the current H5N1 subtype.

Based on seasonal patterns, WOAH said it expects the number of outbreaks in animals to peak in the weeks ahead. It urged countries to maintain surveillance and biosecurity measures and to report the detections in timely manner in poultry and nonpoultry species.

"WOAH also stresses the importance of reporting outbreaks of avian influenza in unusual hosts, as it has been noted that the virus has been increasingly detected in mammals in recent months, a situation that should be monitored," it said, adding that high-quality information is needed to support early detection and response to potential threats to both animals and people.

More detections in US poultry

In the United States, a steady stream of outbreaks continue in poultry. In updates over the past few days, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) reported more outbreaks in three states, including California, Maine, and Wyoming. Most involve backyard flocks, but one of three new outbreaks in California occurred at a commercial duck breeding farm in Merced County that houses 29,100 birds.

So far, the H5N1 outbreaks in the United States, which began in February 2022, have led to the loss of nearly 58.3 million birds across 47 states.

Yes, Humans Can Get The H5N1 Bird Flu, But It’s Rare:-

                                

A strain of bird flu that’s very contagious and deadly among chickens has infected birds in nearly every state in the U.S. It’s called highly pathogenic avian influenza (HPAI) A(H5N1).

As of early January 2023, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) has recorded nearly 58,000 cases in poultry. In late 2021, the virus was detected for the first time in the U.S. Since 2016.

According to the Centers for Disease Control and Prevention, HPAI bird flu infections have a 90-100% mortality rate in chickens, affecting multiple internal organs and causing death within 48 hours. 

News of the disease prompted increased searches on Google by people wondering if the illness could infect humans.

THE QUESTION

Can the H5N1 strain of bird flu currently spreading in the U.S. Infect humans? 

THE SOURCES THE ANSWER

Yes, this bird flu strain can infect humans, but these infections usually only occur when people have close contact with sick birds. It’s rare for the disease to spread from human to human. 

WHAT WE FOUND

It’s possible for people who have contact with birds to catch H5N1 bird flu, but such cases are rare and the Center for Disease Control and Prevention says the disease poses a low risk to the general public. 

The CDC reported the first-ever case of a person with H5N1 in the U.S. In April 2022. The infected person worked closely with sick birds as part of depopulation efforts and recovered after a few days, the CDC said. The World Health Organization reported three other cases worldwide in 2022, one of which resulted in a death in China. 

People who don’t directly interact with birds are unlikely to catch the virus and properly cooked poultry is still safe to eat, the CDC said. 

The virus can be spread from birds to humans through contact with an infected animal’s saliva, mucus and feces, so those most at risk are people like farmers, poultry workers, hunters who may be exposed to sick animals, or people who have backyard chickens. 

Since the virus was identified in the U.S. In late 2021, the CDC said such “sporadic” infections in humans would “not be surprising” since cases have been reported in other countries. However, an infected person is unlikely to spread the illness to another person, the agency said. 

More from VERIFY: No, Sudden Adult Death Syndrome is not linked to vaccines 

“Spread of earlier H5N1 viruses from one infected person to a close contact in the past have happened very rarely and have not led to sustained person-to-person spread,” the CDC said in an April statement about the U.S. Case.

The WHO echoed guidance about the current strain’s lack of transmissibility among humans, but warned about future mutations. 

“While recently-identified avian influenza viruses do not currently transmit easily from person to person, the ongoing circulation of these viruses in poultry is concerning, as these viruses cause severe disease in humans and have the potential to mutate to become more contagious between people,” the WHO said.

While cases in humans are rare, they can be deadly. Since 2003, the WHO collected data from more than 868 human infections occurring in 21 different countries. About 53 percent of infected people died from the illness.

The CDC recommends taking some of the following precautions when dealing with live poultry: 

Wash your hands after collecting eggs, handling birds or being in their living spaces

Adults should supervise children as they wash their hands

Use hand sanitizer after any contact with birds if soap and water aren’t readily available 

Don’t kiss birds or bring them close to your mouth

Don’t bring birds into human living spaces

Avoid getting scratched or bitten by birds

If a person does become infected with HPAI A(H5N1), antiviral medication may help treat the illness, which causes flu-like symptoms including cough and fever, according to the WHO. The CDC also says it has the blueprint for a vaccine that could protect people if the virus started spreading more widely from human to human. 

Experts urge livestock farmers and backyard birders to take steps to protect their animals. Signs bird flu is spreading among backyard poultry include fewer eggs and frequent deaths, the CDC says. The Animal and Plant Health Inspection Service has resources available through its “defend the flock” program. 

“The main action right now is for anyone who owns birds to take steps to help protect the health of their birds. More information on how to do that is available on our website,” a USDA spokesperson told VERIFY.