The chook flu outbreak is the deadliest in U.S. historical past. This is what we all know : NPR


Rescued chickens collect in an aviary at Farm Sanctuary’s Southern California Sanctuary on Oct. 5 in Acton, Calif. A wave of the extremely pathogenic H5N1 avian flu has entered Southern California, pushed by wild chook migration.

Mario Tama/Getty Photos


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Mario Tama/Getty Photos


Rescued chickens collect in an aviary at Farm Sanctuary’s Southern California Sanctuary on Oct. 5 in Acton, Calif. A wave of the extremely pathogenic H5N1 avian flu has entered Southern California, pushed by wild chook migration.

Mario Tama/Getty Photos

The U.S. is enduring an unprecedented poultry well being catastrophe, with a extremely contagious chook flu virus triggering the deaths of some 52.7 million animals.

The perpetrator is extremely pathogenic avian influenza, or HPAI. It has ravaged farm flocks and hen yards in 46 states since February, when the primary circumstances have been reported in industrial flocks.

It is the worst toll on the poultry business since 2014-2015, when greater than 50 million birds died. That earlier outbreak additionally began within the winter — however whereas that ordeal was over by the next June, the present outbreak lasted by way of the summer time and has surged anew.

“I am hopeful that this isn’t the brand new regular for us,” Dr. Richard Webby, director of the World Well being Group’s Collaborating Heart for Research on the the Ecology of Influenza in Animals, tells NPR.

Some birds have died from the illness itself, however the overwhelming majority are being culled by way of flock “depopulation,” to attempt to cease the virus from spreading. That features tens of millions of chickens and turkeys in barns and backyards that had been raised to supply eggs or meat.

This is what you could know concerning the 2022 outbreak within the U.S.:

52,695,450 million birds have been worn out

The losses stretch throughout the U.S., they usually’re deepest within the nation’s center: Greater than 1 million birds have been killed in every of 11 states that stretch from Utah to the Midwest and on to Delaware, in response to the U.S. Division of Agriculture.

In Iowa, two large egg-laying operations needed to cull greater than 5 million birds in single incidents earlier this 12 months.

Not like the 2014-15 outbreak, this one is being pushed by wild birds, not by farm-to-farm transmission. For industrial and yard flocks, many early infections centered alongside the intersection of the Central and Mississippi flyways of migratory wild birds. As these birds traveled, so did the virus.

“We do not know precisely what it’s about it, however it does appear simply to have the ability to develop and transmit higher in wild birds,” Webby, who can also be a member of the infectious ailments division at St. Jude Kids’s Analysis Hospital in Memphis, tells NPR.

“Wild birds are the right mechanism to unfold a virus as a result of they, in fact, fly in every single place,” he provides.

Influenza viruses are frequent amongst wild aquatic birds, which frequently present no signs regardless of being contaminated. In January, the damaging H5N1 flu virus was present in an American wigeon duck in South Carolina — the primary U.S. case since 2016, in response to the Facilities for Illness Management and Prevention. Extra experiences poured in over the next weeks and months, elevating alarms because the virus unfold to extra states.

A extremely pathogenic avian influenza virus “could cause illness that impacts a number of inner organs with mortality as much as 90% to 100% in chickens, typically inside 48 hours,” the CDC notes. “Nonetheless, geese may be contaminated with none indicators of sickness.”


A biosecurity signal is seen on the Powers Farm, which raises turkeys in Townsend, Del. The poultry business has been credited with surveillance and prevention of avian influenza — however the virus stays a menace.

Nathan Howard/Getty Photos


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Nathan Howard/Getty Photos

Avian flu poses solely a low threat to people

It’s totally uncommon for a human to be contaminated with the avian virus. The primary U.S. case of an individual contaminated with avian influenza A (H5N1) virus was reported in April in Colorado. The affected person recovered after experiencing a couple of days of fatigue.

The virus doesn’t pose a particular threat within the nation’s meals provide, given correct dealing with. The CDC states that like all poultry or eggs, heating meals to an inner temperature of 165˚F kills any micro organism and viruses current, together with HPAI viruses.

The virus is sort of a child in a sweet retailer

“The chook populations have not seen viruses like this earlier than,” Webby says, “so when it comes to their immune response, they’re all immunologically naïve to this” influenza virus.

“Proper now, it is like a child in a sweet retailer racing round,” infecting chook populations, he says.

U.S. consultants had been bracing for an outbreak, watching profitable strains of the H5N1 influenza virus proliferate in Europe and elsewhere. Now that the virus is right here, it reveals no signal of going away.

A key a part of the problem, Webby says, is that just like the SARS-CoV-2 virus, the avian flu virus has spun off a number of variants of concern. And proper now, a particular model of the virus — often called clade 2.3.4.4b — is ruling the roost.

“You possibly can consider that like an omicron variant” due to its broad prevalence, Webby says.

Viruses are notoriously fast to mutate. And since its arrival in North America, the avian influenza virus has continued to vary.

“When the virus came visiting into the Americas, it began to work together with the viruses that we’ve in our wild birds right here,” choosing up totally different combos of different genes, Webby says.

Evaluating the present U.S. virus to the one in Europe, Webby says, “From the surface trying in, they appear very comparable. However once you truly go on the within and have a look, the viruses we’ve listed below are fairly totally different now from what was in Europe.”

It is potential that wild chook populations will construct up an immunity to the virus — however Webby warns that it’ll take months to know whether or not that’s occurring at a significant degree.

The outbreak hasn’t raised all poultry prices

In the event you wish to eat hen, you are in luck. This model of the influenza virus would not have an effect on “broilers” — chickens raised for meat — as badly it does “layers” — table-egg laying hens — and turkeys.

“For no matter motive, turkeys and layer birds are usually extra vulnerable” to the virus, says Amy Hagerman, an assistant professor at Oklahoma State College who makes a speciality of agricultural economics.

“The hen that most individuals consider, their hen tenders, their hen sandwiches, all of these issues have not tended to have the identical sorts of affect,” she provides.

Hagerman warns that in a time of inflationary stress and supply-chain snags, it may be laborious to straight hyperlink a worth hike to the virus. However she notes that U.S. egg costs may be affected if only a few farms should get rid of their flocks.


Egg costs have risen this 12 months, as aggressive measures in opposition to avian influenza disrupted the U.S. business. Right here, eggs sit on a grocery store shelf in San Mateo County, Calif.

Liu Guanguan/China Information Service by way of Getty Photos


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Liu Guanguan/China Information Service by way of Getty Photos

“Usually talking, these complexes are over one million birds, simply,” Hagerman says. “It takes fewer egg-laying operations being affected by HPAI to drive up the worth of eggs and egg merchandise,” she provides, particularly because the majority of U.S. manufacturing goes to the home market.

The virus has hit many turkey farms — however as a result of these operations are usually smaller and the circumstances have been unfold out over time and area, producers have principally been capable of take up the losses, increase shares of frozen turkey forward of the end-of-year holidays.

“So, sure, we actually noticed a rise in turkey costs on this vacation season,” Hagerman says, “however not as a lot as we’d have anticipated given the extent of this outbreak.”

What about vaccines?

The presence of the virus within the industrial meals chain raises plenty of potential commerce complications — however so would utilizing a vaccine to combat it.

“Lots of international locations do not use vaccines for this virus of their poultry,” Webby says.

“One of many large problems is timing on a vaccine,” Hagerman says. “Usually you want two doses of a vaccine after which a size of time to attain full effectiveness.”

“In case you have a chook that has a really brief feeding window earlier than it is prepared for harvest, that may be much more difficult since you additionally want to permit the withdrawal interval after the vaccine earlier than the chook is harvested,” she provides.

One other central problem is the issue of surveillance — of understanding whether or not a chook is contaminated with a lethal influenza virus however is not displaying signs as a result of they have been vaccinated.

However the calculations may change if the virus is set to be endemic in wild birds or in a geographic space.

That “actually appears to be the case in Europe and Africa,” Webby says, including, “my intestine feeling is we’re headed that manner within the Americas as effectively.”

“These are literally discussions which might be happening now,” Webby says, describing concepts resembling what sort of post-vaccination surveillance could be wanted to “make sure that your buying and selling companions are pleased that the virus shouldn’t be circulating silently.”

The final outbreak did not survive the summer time. This one did

Specialists say poultry farms needs to be credited with limiting the virus as a lot as they’ve, hailing the success of surveillance and biosecurity packages. However almost 11 months after the primary recognized wild case within the present outbreak, the lethal influenza virus continues to be right here.

“Usually, when the climate will get sizzling, influenza goes away for probably the most half,” Hagerman says.

That was the case within the 2014-2015 outbreak — which got here when Hagerman labored on the U.S. Division of Agriculture’s Animal and Plant Well being Inspection Service, or APHIS.

“Shiny sunshine and warmth kills the virus within the surroundings,” Hagerman says, describing how summer time climate helped finish the sooner outbreak.

“This time we did not see that virus circulation happening to zero in our wild chook inhabitants” over the summer time, Hagerman says. As an alternative, the virus form of simmered by way of the summer time months, she provides, “after which we get into the cooler, wetter months of the autumn and we see a resurgence.”

The lengthy outbreak is discouraging, Hagerman says: “If we take a look at Europe, we will see that they’re on two years of HPAI outbreaks.”

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