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Deadly Pig Virus Enters U.S.

Deadly Pig Virus Enters U.S.

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The nation’s pigs and pork industry are threatened by a deadly virus that somehow made its way into the United States

A virus called porcine epidemic diarrhea virus, which causes diarrhea and vomiting in pigs, is infecting pigs in 14 states.

A deadly virus that causes diarrhea and vomiting in pigs has entered the United States and has infected pigs in 14 states, according to Scientific American.

Scientists are trying to track the virus and prevent its spread as an outbreak could cost the United States’ pork industry millions of dollars.

The virus called porcine epidemic diarrhea virus (PEDV), spreads quickly by a fecal-oral route and can infect entire herds.

“How this virus got here, that’s the million-dollar question,” says James Collins, director of the Veterinary Diagnostic Laboratory at the University of Minnesota in Saint Paul.

It was first discovered in the United Kingdom in 1971 and caused wide outbreaks in Europe in the 1970s and 1980s. After pigs in those areas developed immunity to the virus, it died off and only caused occasional outbreaks. Since then, it has spread to Asia, where it has been endemic since 1982 and has caused considerable economic losses to pork producers.

Adult pigs typically recover from the virus, but it can kill 80 to 100 percent of infected piglets. However, it poses no health threat to humans.

The U.S. Department of Agriculture has attempted to keep PEDV out of the country by restricting imports of pigs and pork products from certain infected nations such as China. On May 10, however, the Veterinary Diagnostic Laboratory at Iowa State University in Ames found that PEDV had infected pigs in Iowa, the leading producer of the nations’ pork, and the first known case was found earlier in Ohio from samples submitted on April 16.

Deadly Swine Fever Is Ravaging China's Pork Industry, and It May Be Spreading

A long the Gulf shores of Texas and Louisiana there is a complex of deep, underground caverns. Inside each of these enormous caves – each of which is large enough to easily fit Chicago’s Willis Tower inside &mdash the U.S. government keeps hundreds of millions of barrels of petroleum to safeguard the country against natural-disaster-induced and political-conflict-related supply disruptions.

Many countries have similar strategic reserves, but on the other side of the world, China maintains a different kind of stockpile: icy warehouses around the country are filled with frozen pork. The commodity is of such importance in China &mdash which consumes more pork per capita than any other country after Vietnam &mdash that the government set up a national reserve to protect the country from shortages and price volatility.

But the country’s pork industry is being devastated by a deadly, highly-contagious virus. Since officials began reporting cases last August, African Swine Fever (commonly known by its abbreviation ASF), has swept across the country. Outbreaks have hit every province and all five autonomous regions (like Tibet and Mongolia), and experts believe there are far more cases than the 129 outbreaks officially reported.

“There are many reports of cover-ups in China,” Brett Stuart, co-founder of analysis firm Global AgriTrends told TIME. He said a farm manager was reportedly jailed after reporting a case in Shandong province, suggesting authorities could be trying to obscure the reach of the problem.

The latest cases in China’s southern Hainan island &mdash a waterway and more than 2,000 miles from the northeastern province of Liaoning where ASF was first reported &mdash show how quickly the virus can spread. ASF, for which there is no cure or vaccine, can be passed between sick animals, or from objects like a farmer’s clothing and boots.

Consumption of infected meat &mdash the resilient disease can live for months in pork products like sausage &mdash is a major contributor to its spread in China, where many small famers feed their pigs household garbage, although the government has now placed restrictions on swill feeding. ASF is not known to be harmful to humans.

Experts say that the disease has moved more rapidly in Asia than in other regions where outbreaks have been found, like Europe.

“I have been very surprised about how fast ASF has spread in China,” Dr. Linda Dixon, an ASF researcher at the Pirbright Institute, a research institute dedicated to studying infectious disease in farm animals, told TIME.

Widespread culls have been enacted to fight the spread of ASF. Data released by China’s National Bureau of Statistics show that pig numbers decreased to 375.3 million, a drop of 40 million, at the end of March from one year earlier, according to the Wall Street Journal. China&rsquos Ministry of Agriculture and Rural Affairs believes the situation is worse, estimating that pigs have decreased 19% year-on-year, says the Journal.

“The impact on China&rsquos pork industry has been catastrophic. Farms are empty across China. Farmers have been directed to wait up to [six] months before restocking,” says Stuart, of Global AgriTrends.

The decline in China’s pig stocks could seriously impact meat production at a time at a time when trade tensions are high. Chenjun Pan, Senior Analyst at Rabobank, told TIME that production could fall as much as 25-35% in 2019, and some experts believe China will be reliant on U.S. pork to keep its population fed.

China has imposed retaliatory tariffs of 50% on U.S. pork imports, which brings the total tariff level to 62% when factoring in the normal 12% rate applied to U.S. pork brought into the country. The USDA estimates that China will be the biggest source of demand for U.S. pork in 2019, and they expect China’s imports to rise 41% for the year.

“China&rsquos need for pork will make it hard to ignore the U.S. It is logistically and physically impossible to find enough pork to fill China&rsquos impeding pork gap,” says Stuart, of Global AgriTrends.

And the disease appears to be spreading. Vietnam reported its first outbreak in February, and Cambodia confirmed the virus’ arrival in March. In the last few weeks, more cases have been reported near Cambodia’s border with Vietnam.

Customs authorities worldwide are on alert. Tourists arriving in Taiwan were fined for bringing pork products into the country, and ASF was discovered in sausage confiscated at a Japanese airport. In March, U.S. customs officials seized a million pounds of Chinese pork on swine fever concerns.

According to Dixon, of the Pirbright Institute, it seems “likely” that ASF will spread further across Southeast Asia due to large pig populations living in small farms. Laos has already put a hold on the import of pigs and pork products from China. In early April, Thailand approved funding to prepare the country for a potential outbreak.

Sheepdrove’s Weblog

The H1N1 swine flu virus in North America currently concerning global public health officials is not the first triple hybrid human/bird/pig flu virus to be discovered. The first was discovered in a North Carolina factory farm in 1998. Since the 1918 pandemic, an H1N1 flu virus has circulated in pig populations, becoming one of the most common causes of respiratory disease on North American pig farms.

In August 1998, however, a barking cough resounded throughout a North Carolina pig farm in which all the thousands of breeding sows fell ill. An aggressive H3N2 virus was discovered, the type of influenza that had been circulating in humans since 1968. Not only was this highly unusual—only a single strain of human virus had ever previously been isolated from an American pig population—but upon sequencing of the viral genome, researchers found that it was not just a double reassortment (a hybrid of human and pig virus, for example) but a never-before-described triple reassortment, a hybrid of three viruses—a human virus, a pig virus, and a bird virus.

Dr. Robert Webster, one of the world’s leading experts of flu virus evolution, blames the emergence of the 1998 virus on the “recently evolving intensive farming practice in the USA, of raising pigs and poultry in adjacent sheds with the same staff,” a practice he calls “unsound.” “Within the swine population, we now have a mammalian-adapted virus that is extremely promiscuous,” explained another molecular virologist at the time, referring to the virus’s proclivity to continue to snatch up genes from human flu viruses. “We could end up with a dangerous virus.” This may indeed be what we are now facing.

Within months of the 1998 emergence, the virus showed up in Texas, Minnesota, and Iowa. Within a year, it had spread across the United States. This rapid dissemination across the country has been blamed on long-distance live animal transport. In the United States, pigs travel coast to coast. They can be bred in North Carolina, fattened in the corn belt of Iowa, and slaughtered in California. While this may reduce short-term costs for the pork industry, the highly contagious nature of diseases like influenza (perhaps made further infectious by the stresses of transport) needs to be considered when calculating the true cost of long-distance live animal transport.

What led to the emergence of the North Carolina strain in the first place? What changed in the years leading up to 1998 that facilitated the surfacing of such a unique strain? It is likely no coincidence that the virus emerged in North Carolina, the home of the nation’s largest pig farm. North Carolina has the densest pig population in North America and reportedly boasts more than twice as many corporate swine mega-factories as any other state.

The year of emergence, 1998, was the year North Carolina’s pig population hit ten million, up from two million just six years before. At the same time, the number of hog farms was decreasing, from 15,000 in 1986 to 3,600 in 2000. How do five times more animals fit on almost five times fewer farms? By crowding about 25 times more pigs into each operation. In the 1980s, more than 85% of all North Carolina pig farms had fewer than 100 animals. By the end of the 1990s, operations confining more than 1,000 animals controlled about 99% of the state’s inventory. Given that the primary route of swine flu transmission is thought to be the same as human flu—via droplets or aerosols of infected nasal secretions —it’s no wonder experts blame overcrowding for the emergence of new flu virus mutants.

Starting in the early 1990s, the U.S. pig industry restructured itself after Tyson’s profitable poultry model of massive industrial-sized units. As a headline in the trade journal National Hog Farmer announced, “Overcrowding Pigs Pays—If It’s Managed Properly.” The majority of U.S. pig farms now confine more than 5,000 animals each. A veterinary pathologist from the University of Minnesota stated the obvious in Science: “With a group of 5,000 animals, if a novel virus shows up it will have more opportunity to replicate and potentially spread than in a group of 100 pigs on a small farm.”

The swine flu virus discovered this week in California and Mexico appears to be a quadruple reassortment virus incorporating genes from human and avian flu viruses as well as North American and European strains of swine flu. In Europe in 1993, a bird flu virus had adapted to pigs, acquiring a few human flu virus genes, and infected two young Dutch children, even displaying evidence of limited human-to-human transmission.

“Influenza [in pigs] is closely correlated with pig density,” said a European Commission-funded researcher studying the situation in Europe. As such, Europe’s rapidly intensifying pig industry has been described in Science as “a recipe for disaster.” Some researchers have speculated that the next pandemic could arise out of “Europe’s crowded pig barns.” The European Commission’s agricultural directorate warns that the “concentration of production is giving rise to an increasing risk of disease epidemics.” Concern over epidemic disease is so great that Danish laws have capped the number of pigs per farm and put a ceiling on the total number of pigs allowed to be raised in the country. No such limit exists in the United States.

Influenza pandemics

The 1918 influenza pandemic swept the world within months, killing an estimated 50 million people — more than any other illness in recorded history for the short time frame involved. The H1N1 influenza virus that infected more than one-third of the globe had an avian origin. First identified in the United States by military personnel in the spring of 1918, the virus killed an estimated 675,000 Americans, according to the Centers for Disease Control and Prevention (CDC).

Unlike some flu strains that mainly kill the elderly and those with compromised immune systems, the 1918 strain hit young adults hardest, as the older population seemed to have some immunity built up from a past H1N1 virus. In one year, the average life expectancy in the United States dropped by 12 years.

Another H1N1 virus, this one called (H1N1)pdm09 cropped up in the spring of 2009 and lasted until the next spring, with the CDC estimating some 60.8 million cases and 12,469 deaths in the U.S. Worldwide, the virus killed between 151,700 and 575,400 individuals, the CDC estimates. That virus appears to have originated in pig herds, with a so-called reassortment of influenza viruses — when the viruses swap genetic information — occurring naturally in North American and Eurasian pig herds.

As Pig Virus Spreads, The Price Of Pork Continues To Rise

Michael Yezzi raises 1,000 pigs a year in Shushan, N.Y. He's worried about how to keep his farm safe from a disease that has no proven cure.

Abbie Fentress Swanson for NPR

If you're bringing home the bacon, you may have noticed a price tag inching upward.

Consumers are paying nearly 13 percent more for pork at the supermarket than they were this time last year, according to the U.S. Department of Agriculture. A deadly pig disease is partially to blame.

Porcine epidemic diarrhea virus, or PEDv, has killed more than 7 million piglets in the past year, and the number of cases is on the rise. Many hog producers are worried about how to keep their farms immune from a disease that has no proven cure.

"The disease is very serious and if it hits a farm, there is near 100 percent mortality for piglets below a certain age, which is a significant loss on any farm," says Michael Yezzi, who raises about 1,000 hogs a year at Flying Pigs Farm in Shushan, N.Y. "And while it doesn't kill the older pigs, it impacts the growth of the pigs remaining on the farm."

The Salt

Pig Virus Continues To Spread, Raising Fears Of Pricier Bacon

The Salt

'Piglet Smoothie' Fed To Sows To Prevent Disease Activists Outraged

PEDv first appeared in the U.S. in April 2013. Since then, the virus has infected more than 4,700 farms in 30 states. Scientists do not believe the disease can be transmitted to humans. But research is ongoing about the origin of the virus, whether previously infected sows can catch the disease more than once and exactly how PEDv is spread.

"It's a delicate balance because you don't want to raise people's concerns, because that could have a negative impact on the market. You don't want to raise people's concerns, because export activities could be impacted," Agriculture Secretary Tom Vilsack said on the USDA's daily radio report.

But Vilsack said the continued spread of the disease and newly detected strains of the virus moved the USDA to take a more aggressive stance. In early June, the department announced that it would spend $26.2 million to eradicate PEDv.

The USDA approved the use of a vaccine that may protect piglets from the disease, even though it's still being tested in commercial settings, and issued a federal order requiring hog producers to report new cases of PEDv or of the related disease porcine delta coronavirus. And farmers are being urged to put common-sense biosecurity measures in place, like disinfecting facilities and trucks, and ensuring workers are wearing clean clothes.

"PEDv has been pretty devastating to the industry, but we have very strict biosecurity standards," said Bob Ruth, president of Country View Family Farms, which raises 1 million hogs a year in Pennsylvania, Ohio and Indiana. "One of the things we're looking to do is isolate the trucks we use to haul the animals."

On the Clinton Corners, N.Y., farm where he raises show piglets, Clayton Stephens requires visitors to wear disposable plastic boots over shoes and doesn't permit visitors to enter his barn if they have recently been on other hog farms.

At Clayton Stephens' farm, he's implemented biosecurity measures to try to keep the disease away from his hogs. Abbie Fentress Swanson for NPR hide caption

At Clayton Stephens' farm, he's implemented biosecurity measures to try to keep the disease away from his hogs.

Abbie Fentress Swanson for NPR

"It's not a matter of if [hog producers] are going to get it it's when they're going to get it," says Stephens. "I think everybody's going to end up having it. They're trying to keep it out as long as they can."

More than a dozen state fairs across the country are also taking measures to slow the spread of the disease.

"We did make the recommendation to the state fair that they not have nursing piglets with sows this year," says New York State Veterinarian Dave Smith. "We do know that PEDv is devastating to piglets under 10 days of age and we really do not want to see a bunch of sick and dying piglets at the fair. It's an exhibit that no one needs to see."

Other states, including Virginia, South Dakota and Ohio, have canceled certain hog shows or are requiring that pigs be taken to the slaughterhouse right after the fair. But it remains to be seen whether tightening up biosecurity will keep piglets from dying from PEDv.

"They don't know where this disease is coming from," says Yezzi. "Even closed operations that aren't getting pigs in from the outside have gotten this, even with the strictest biosecurity situations. So everybody's at risk."

Meanwhile, economists predict that farmers will reduce the size of their herds this year to minimize costs should PEDv infect their operations. Consumers can also expect pork prices, which now average almost $4 a pound, to continue to rise during the second half of 2014.

Abbie Fentress Swanson is a freelance reporter based in New York.

From a bat, to a pig, to you — not likely

A bat settles in a palm tree, somewhere in southern China. It nibbles on a piece of fruit, and later it drops part of it in a pigpen, where it is eaten by a piglet. The piglet is slaughtered. A chef who handles the meat shakes hands with Gwyneth Paltrow, who then goes back to the U.S., visits her lover, stumbles home, shakes, foams at the mouth and dies.

And with that, a vicious viral killer begins its rampage.

This scenario from the movie “Contagion” was dreamed up by a Columbia University professor of epidemiology, W. Ian Lipkin, which gives it a veneer of scientific respectability. But could a deadly new disease really emerge this way? Uh — not likely.

It isn’t that diseases don’t cross from one species to another all the time they do. Most human diseases are zoonoses (infections originating in animals). Smallpox, for example, began life as a rodent pox that gradually evolved into a human disease. The most vicious form of malaria, falciparum malaria, is today a human illness, but it too started life as a disease of other animals. HIV started in chimps, and it probably crossed into our species sometime in the first half of the 20th century.

All of these transformations depended on natural selection, the force that molds all living things, from pigs to parasites to people, and natural selection isn’t like flicking a switch. It’s a process. And it takes time for a disease to become efficient in a new species.

To imagine that this sort of adaptation could happen in two days is to leap onto Fantasy Island. Casual contact between species does not create new diseases in a flash. We’re supposed to think that a new virus, part of bat origin, part of pig, sprang into being like magic as the new bits of RNA re-assorted themselves in the piglet. Bingo! You’ve got a new human virus. And miracle of miracles: It explodes! All across the world!

I asked Lipkin, science advisor to the movie, to explain his thinking. Here’s how he responded in an email: “A recombination event … is what we proposed in ‘Contagion.’ A pig infected with one virus became infected by another and the two genomes combined in a single cell infected with both to form a virus with the capacity for human-to-human transmission and to cause more morbidity and mortality. Such events are eminently plausible and have been detected by sequencing a wide range of viruses.”

But if such events are “eminently plausible,” why haven’t we seen new, highly transmissible, deadly human viruses that arose this way?

It isn’t all that rare for RNA viruses to exchange genes in a cell. But to assume that a new, fully functional pathogen can arise de novo in a single pig and instantly become a lethal, highly transmissible, human-adapted virus is like believing that Aphrodite arose perfect from the foam. Mutation and recombination are only the raw material upon which natural selection acts. The “Contagion” scenario removes natural selection from the process.

The real-life inspiration for the movie was the Nipah virus, which does infect fruit bats, palm sap and pigs. Sometimes pig farmers catch it from their animals, sometimes people get it straight from palm sap that has been contaminated by infected bats. Nipah virus has been known to spread person to person, but only under conditions involving prolonged, close physical contact. In this way it’s much like Ebola, an animal virus much better adapted to its original host than to people.

To turn into an effective human pathogen, a germ has to be able to spread easily among humans. That means it has to make the human host shed it into the outside environment where it can be picked up by another host. Transmission is a subtle business, and the ability to transmit, to manipulate the host into producing symptoms that get the germ out of one body and into the next, has to evolve. That evolution can take place only by the germ cycling among people. Not bats. Not pigs. People. And enough of them that the virus gets better and better adapted to its new hosts. Only then can it turn, temporarily or permanently, into a human-adapted germ.

That process was starting to happen with SARS (severe acute respiratory syndrome), a disease that broke out of the “wet markets” of southern China in 2003 and was carried, via air travel, around the world. It infected about 8,000 people and killed 800 of them. But SARS, though a fairly lethal disease, wasn’t very effective at transmission, which occurred only late in the course of illness and chiefly in hospitals, where putting very sick people on respirators aerosolized the virus and helped it spread. Quarantine of exposed people and isolation of the sick sufficed, within months, to break the chains of transmission and drive the evolving virus out of existence.

If the filmmakers had wanted to show a novel virus breaking into humanity in a way that approximates the truth, they would have shown us SARS, a nasty, lethal but inefficient human pathogen that the oldest of methods — quarantine and isolation — sufficed to push off the Earth. But that wouldn’t have been as dramatic.

The truth is that if new diseases erupted the way that “Contagion” and its science advisors suggest, we’d all have died a long time ago. We are too much a single planet we are 7 billion people practically sitting in each other’s laps, as science-fiction writer Robert Heinlein might say. It’s fortunate that even if filmmakers forget natural selection and its stringencies, pathogens don’t. That’s why we are still here to argue about it.

Wendy Orent is the author of “Plague: The Mysterious Past and Terrifying Future of the World’s Most Dangerous Disease.”

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Deadly Swine Flu Outbreak Linked To Smithfield’s CAFOs

Thus far, more than 1000 people in Mexico, Texas, and California have been infected with a deadly new strain of virus that has killed at least 68 people. The World Health Organization (WHO) warned today that this new virus (called the “swine flu” although it’s a genetic mix of avian, human, and swine flus) has many of the traits of an emerging global pandemic.

That alone is scary news. Roughly 7% of the people who’ve gotten this disease are already dead. That, too, is scary.

But the scariest news of all? They believe this super virus originated in factory farmed pigs.

Confined Animal Feeding Operations (CAFOs) for pigs are about as grotesque as they can come. Pigs are crammed into giant buildings, kept in stalls so small they can’t even turn around. The pollution from their waste is so noxious that you must wear a gas mask to enter the building. And, of course, the pig’s immune systems are so weakened that you must don a “clean suit” just to walk within 100 feet of them.

In Mexico, where standards are more lax than in the United States, the story is even worse.

On Friday, the U.S. disease-tracking blog Biosurveillance published a timeline of the outbreak containing this nugget, dated April 6 (major tip of the hat to Paula Hay, who alerted me to the Smithfield link on the Comfood listserv and has written about it on her blog, Peak Oil Entrepreneur):

Residents [of Perote] believed the outbreak had been caused by contamination from pig breeding farms located in the area. They believed that the farms, operated by Granjas Carroll, polluted the atmosphere and local water bodies, which in turn led to the disease outbreak. According to residents, the company denied responsibility for the outbreak and attributed the cases to “flu.” However, a municipal health official stated that preliminary investigations indicated that the disease vector was a type of fly that reproduces in pig waste and that the outbreak was linked to the pig farms.

The real kicker? Thus far, the possible connection to Smithfield’s Mexican operation (Granjas Carroll, above) has not been reported in the U.S. news media.

But it’s all over the Mexican media. The stories tell of giant open air cesspools of improperly treated pig waste creating massive air and water pollution and a breeding ground for virulent pathogens. “Clouds of flies” swarm over the waste and are the most likely carriers of this new and deadly disease. Now 30% of the area residents around the operation are infected with this new swine flu, and residents are demanding the Mexican government examine Smithfield’s Mexican hog operations as a potential culprit.

The Mexican government’s response? Silence.

Why does this scare me?

Because although a bit more regulated, our factory hog farms are no less pristine. Just last year the Pew Commission on Industrial Farm and Animal Production warned of emerging forms of avian-swine-human influenza viruses here in the U.S.

The continual cycling of swine influenza viruses and other animal pathogens in large herds or flocks provides increased opportunity for the generation of novel viruses through mutation or recombinant events that could result in more efficient human-to-human transmission of these viruses. In addition, agricultural workers serve as a bridging population between their communities and the animals in large confinement facilities. This bridging increases the risk of novel virus generation in that human viruses may enter the herds or flocks and adapt to the animals.

Reassortant influenza viruses with human components have ravaged the modern swine industry. Such novel viruses not only put the workers and animals at risk of infections, but also potentially increase zoonotic disease transmission risk to the communities where the workers live. For instance, 64% of 63 persons exposed to humans infected with H7N7 avian influenza virus had serological evidence of H7N7 infection following the 2003 Netherlands avian influenza outbreak in poultry. Similarly, the spouses of swine workers who had no direct contact with pigs had increased odds of antibodies against swine influenza virus. Recent modeling work has shown that among communities where a large number of CAFO workers live, there is great potential for these workers to accelerate pandemic influenza virus transmission.

In other words, they feared that an avian flu virus would get into a swine CAFO, mutate into something much more virulent, and then get passed to humans.

Sounds just like what happened in Mexico.
PEOPLE! We must put an end to CAFOs and factory farmed meats.

  • They are inhumane.
  • They produce unhealthy meats when compared to their grass-fed/wild/foraged counterparts.
  • They pollute area water and air supplies leading to increased respiratory problems and cancer rates for nearby residents.
  • And now we know they are a dangerous vehicle for the creation and spreading of lethal diseases.

What more evidence do we need?

Whatever we do — no matter how tight our pocket books — we must not support these operations with our food dollars.

Friends, please, please, please consider this an urgent plea to only buy humanely raised, CLEAN meat from sustainable farming operations. If you haven’t yet made the switch, let this be your motivation to do so.

Lassa Fever (continued): Outbreak in Nigeria

Pius Utomi Ekpei/AFP/Getty Images

According to the Nigeria Centre for Disease Control, there is currently an outbreak centered in southwest Nigeria.

As of mid February 2020, more than 100 people had died from this outbreak.


EBV spreads most commonly through bodily fluids, especially saliva. However, EBV can also spread through blood and semen during sexual contact, blood transfusions, and organ transplantations.

EBV can be spread by using objects, such as a toothbrush or drinking glass, that an infected person recently used. The virus probably survives on an object at least as long as the object remains moist.

The first time you get infected with EBV (primary EBV infection) you can spread the virus for weeks and even before you have symptoms. Once the virus is in your body, it stays there in a latent (inactive) state. If the virus reactivates, you can potentially spread EBV to others no matter how much time has passed since the initial infection.

How Do We Stop The Next Pandemic? Here's A New Strategy

In movies such as Contagion, a pandemic begins in a flash. A deadly virus spills over from an animal, like a pig, into humans and then quickly triggers an outbreak.

But that's not actually what happens, says Dr. Gregory Gray at the Duke Global Health Institute. "It's not like in the movies," he says, "where this virus goes from a pig in Indonesia and causes a pandemic."

Over the past few decades, the U.S. government has spent hundreds of millions of dollars hunting down new viruses in animals, largely wild animals, in hopes of stopping a pandemic. And yet those efforts failed to find – and stop — SARS-CoV-2, the virus that causes COVID-19, before it spread around the world.

Now, writing in the journal Viruses, Gray and his colleagues propose an alternative approach to hunting down new viruses, which, they believe, will have a better chance of stopping the next pandemic.

The approach takes into account the latest information about how human pathogens emerge from wildlife and how pandemics begin.

Almost all viral infections come from animals, says virus expert Eddie Holmes at the University of Sydney. The virus hangs out in an animal — say a bat, pig or bird — for centuries, even millennia. And when given the opportunity, it jumps into a person. Scientists call this process "spillover."

Some viruses are particularly good at spilling over, and so they do it much more frequently. "Unfortunately, coronavirus is in that category," Holmes says. "If you look at the evolution of coronavirus, you see a lot of jumping around from host to host."

That's why scientists are so concerned about another coronavirus erupting — and causing a future pandemic. But which one?

There are likely thousands of coronaviruses across the planet living in virtually all animals, Holmes says. Finding the next "big one" is like looking for a submicroscopic needle in a haystack scattered across the globe — in forests, farms and caves.

For decades, scientists have hunted for undiscovered viruses before the spillover occurs. Specifically, they've looked for viruses inside wild animals, such as bats, where SARS-CoV-2 originates. They've trapped tens of thousands of bats, individually, and then taken samples from their saliva, feces and blood. (Here at Goats and Soda, we have reported on several studies such as this in Southeast Asia and in West Africa.)

This process is time-consuming, expensive, and, as Gray points out, it failed to stop the COVID-19 pandemic.

Why? Gray says one reason is you can't tell which viruses in the bats are going to be dangerous to people — and which ones will never leave the bats.

"These projects have discovered a lot of viruses, but those viruses have not always — and frankly, infrequently — been associated with illness in humans," he says.

But what if there is an approach to focus only on the viruses that are already spilling over into humans and making some people sick. "We'll get more bang for our buck. It'll be more efficient, and we'll pick up more viruses that are threatening people," he says.

What Gray and others are starting to realize is that virus spillover works a bit differently than how scientists originally thought. For starters, spillovers aren't rare. There are many hidden spillovers happening every day, Gray says.

"[New] viruses are assaulting humans' immune systems all the time," he says, especially for people who work closely and frequently with animals, such as farmers and ranchers.

But the vast majority of these spillovers are dead ends. A virus may jump into a person or two. And it might make them sick. But at this point, the virus doesn't have the ability to spread from one person to the next. And so the outbreak stops.

If the virus has the opportunity to spill over and over again, it may begin to evolve in ways to evade the human immune system and possibly even escape from the human body. At that point, the virus may begin to spread from one person to the next.

"The virus has to take hold. It has to adapt and then it can become highly transmissible," Gray says. "Evolutionary science would suggest that it's a process."

This step-by-step process takes years, decades, even centuries. And, Gray says, it gives scientists a more efficient way to zero in on the viruses in animals that are most dangerous to people. "We can catch viruses while they're crossing over before they fully adapted to humans," he says.

To do that, Gray says, scientists need to look inside people who are constantly in contact with animals, who are mostly likely to get sick from the initial spillovers before a virus becomes contagious.

For example, Gray and his colleagues recently searched for undiscovered coronaviruses in people sick with pneumonia — and quickly found one. The team screened about 400 samples from pneumonia patients in Sarawak in Malaysia. They found at least four people infected with a new coronavirus that likely came from an animal.

"I can't get into too many details because it's not published yet," he says. "But there's an inkling that other researchers are using a similar strategy, and they may have found another [new] virus, too."

In other words, this alternative approach may have already caught not one, but two new coronavirus pathogens, before a big outbreak has occurred.

Over the past few decades, the U.S. government has spent hundreds of millions of dollars hunting down viruses all over the world in hopes of stopping a pandemic. Well, those efforts failed to find and stop COVID-19. Now one group of researchers is proposing a different approach, one that might have a better chance of stopping the next pandemic. NPR's Michaeleen Doucleff reports.

MICHAELEEN DOUCLEFF, BYLINE: Almost all human viruses, including SARS-CoV-2, come from animals. When an animal virus jumps into people, scientists call it a spillover.

EDWARD HOLMES: Viruses spill over as part of their daily humdrum life. That's what they do.

DOUCLEFF: That's Edward Holmes. He's a virologist at the University of Sydney. He says some viruses are better at spilling over than others, and they tend to do it more often.

HOLMES: And unfortunately, coronaviruses are in that category. If you look at the evolution of coronavirus, you see lots of jumping around. They're just jumping between hosts.

DOUCLEFF: That's why scientists are so concerned about another coronavirus erupting and causing a future pandemic. But the big question is, which one? Holmes says there are thousands upon thousands of coronaviruses out there in virtually all animals.

HOLMES: The virosphere of coronavirus is just immense, and we're only just starting to scratch the surface.

DOUCLEFF: For decades, scientists have hunted for undiscovered viruses inside wild animals like bats, where SARS-CoV-2 comes from. They've trapped thousands of bats individually, drew their blood, sampled their spit. This process is time-consuming and expensive, and it failed to stop the COVID-19 pandemic. Why? Dr. Gregory Gray is an infectious disease epidemiologist at Duke University. He says one reason is you can't tell which viruses are going to be dangerous to people and which ones will never leave the bats.

GREGORY GRAY: They've discovered a lot of viruses, but those viruses have not always - in fact, infrequently - been associated with illness in man.

DOUCLEFF: Now Gray and his colleagues, writing in the journal Viruses, propose a different approach.

GRAY: We'll get more bang for our buck. It'll be more efficient. We'll pick up more viruses that are threatening man, and we can do this at less cost.

DOUCLEFF: What Gray and others are starting to realize is that virus spillover works a bit differently than what scientists originally thought and the way it's been portrayed in pop culture.

GRAY: It's not like in the movies, where a virus goes from a pig in Indonesia to cause a pandemic.

DOUCLEFF: Instead, it takes time - years and even decades. And it occurs in several distinct stages.

GRAY: The evolutionary science would suggest that it's a progression.

DOUCLEFF: At the beginning, a virus may jump into a person or two, and it might make them sick. But at this point, the virus doesn't have the ability to spread from one person to the next, and so the spillover stops. But then if the virus has the opportunity to spill over again and again hundreds, even thousands of times, it gives the virus the opportunity to figure out humans and how to spread between them.

GRAY: You know, it has to take hold. It has to adapt and then become highly transmissible.

DOUCLEFF: The stepwise process, Gray says, gives scientists a more efficient way to zero in on the viruses in animals that are most dangerous to people.

GRAY: Catch them while they're crossing over before they've fully adapted.

DOUCLEFF: So instead of trapping and screening wild animals for viruses, Gray says scientists need to look inside people who are constantly working with animals, particularly farmed animals, people getting the infections from those initial spillovers, especially people getting sick with pneumonia or COVID-like symptoms.

GRAY: We would see what pathogens are already beginning to take hold and the humans so we have time to develop mitigation strategies.

DOUCLEFF: Gray and his colleagues have already started using this strategy in Southeast Asia. He and his team screened about 400 patients with pneumonia in Borneo and found that at least four of them likely were infected with a new, undiscovered coronavirus. Michaeleen Doucleff, NPR News. Transcript provided by NPR, Copyright NPR.