National Geographic News
Photo of a pig silhouetted at twilight.

A pig walks on a Minnesota farm in 1987. A tablespoon of infected manure would be enough to infect the entire U.S. hog herd, according to one expert.

Photograph by Richard Hamilton Smith, Corbis

Reed Karaim

for National Geographic

Published May 1, 2014

This story is part of National Geographic's special eight-month Future of Food series.

A virus that has wiped out as many as seven million pigs in the United States during the past year is pushing the price of pork to record highs and contributing to rising overall meat costs.

Porcine epidemic diarrhea virus, or PEDv, largely escaped public attention until recently, but the National Pork Producers Council (NPPC) estimates it has already killed 10 percent of the country's pigs. Other estimates, including those of the U.S. Department of Agriculture, are lower, with losses projected in the 5 to 7 percent range.

The virus is highly unlikely to pose a direct threat to humans, according to health experts. But across the United States, individual farmers have had to deal with thousands of sick and dying baby pigs, an impact that Howard Hill, president of the NPPC, has described as "heartbreaking."

Adult hogs usually recover from the virus after a few days, and mothers eventually build up resistance to the disease. Once sows develop resistance, they no longer pass the disease to their offspring. But that process can take three weeks to a month, and during that time, the newborn piglets die.

Virus "Scares the Tar Out of You"

Losses can be catastrophic. Greg Lear, a hog producer near Spencer, Iowa, says the disease showed up in his barns on December 21 last year, and he and his employees were soon overwhelmed. "It was about 850 little pigs that didn't make it," he says. "For three weeks, it was 100 percent death. It was really tough."

PEDv first appeared in the United States in Ohio last May, and has since spread to 30 states. Rodney "Butch" Baker, a swine biosecurity specialist at Iowa State University in Ames, recently told Reuters that about "a tablespoon of PEDv-infected manure is roughly enough to infect the entire U.S. hog herd."

"It just scares the tar out of you how much of this virus is out there and how easily it can be spread," says Lear.

Leap to Humans Unlikely

The possibility that the disease could make the leap to humans cannot be completely ruled out, according to two specialists on zoonotic viruses (disease pathogens that jump from one species to another), but it is highly unlikely.

Christopher Olsen, a professor of public health at the University of Wisconsin in Madison, and Juergen Richt, a distinguished professor of veterinary medicine at Kansas State University in Manhattan, say PEDv is part of a family of coronaviruses that includes the SARS respiratory virus and others that have jumped from an animal host to humans.

Still, PEDv first appeared in England in 1971, and it hasn't jumped species yet. "This disease has been around for more than 40 years in pigs in Europe, Asia, and now the United States, and there has been no evidence that anyone working with the pigs in any of that time has caught the disease," says Richt.

Says Olsen: "There is no evidence it poses a risk to people, and there is no evidence of any human infection."

Researchers are unsure how the disease got into United States, although some speculate it may have been carried by dried blood added to pig food as a protein supplement.

"To me, the big question is, how did this biological agent come into our country with all our import regulations?" says Richt, who also serves as director of a Department of Homeland Security center that aims to protect the country from foreign animal diseases. "We need to understand in detail how it came here in order to protect our pig herd from other diseases that are even more dangerous." Richt cited foot-and-mouth disease and classical swine fever, which the USDA says have been eradicated in the United States, as greater potential threats.

Pork Still Safe, but Pricey

PEDv does not make pork unsafe to eat, according to health experts. The virus attacks the gastrointestinal tracts of pigs, not the meat. And cooking kills the virus in any case, says Olsen, adding that a small amount would unlikely cause harm even if a person did somehow ingest it.

"It's important to emphasize that there's absolutely no reason not to continue eating pork," Olsen says. "I had bacon for breakfast this morning."

PEDv is making pork more expensive, however. The NPPC believes prices could rise 10 to 12 percent. Chris Hurt, a professor of agricultural economics at Purdue University in West Lafayette, Indiana, projects a more modest increase of 7 percent.

Hurt notes that even before the virus hit, pork prices were up significantly in 2013. The average price for all cuts of pork last year was $3.64 a pound, and Hurt believes it will jump to $3.90. "That will be a record high," he says.

Prices of meat generally have been high, due in part to the ongoing drought through much of the cattle-grazing lands of the West, and in part to high animal-feed prices. PEDv has added to the problem, Hurt says. The U.S. Bureau of Labor Statistics found that prices for the food category "meats, poultry, fish, and eggs" jumped 5.1 percent in March from a year earlier.

While grocery shoppers are feeling the pinch, hog farmers could actually come out ahead. In prepared testimony before a House agricultural panel Wednesday, Hill, the NPPC's president, noted the industry could enjoy perhaps its best year ever financially.

"Producers on average get compensated for their losses by high prices," explains Hurt, the Purdue professor. "The real cost of the disease is borne by consumers."

In our rapidly changing, globalized world, we all need to understand how food has made us who we are today and how it shapes our future. Starting with the May issue of National Geographic magazine and continuing through 2014, National Geographic explores our complex relationship with what we eat and where our food comes from.

Anna  Wallace
Anna Wallace

This article disgusts me.  "It's important to emphasize that there's absolutely no reason not to continue eating pork...The real cost of the disease is borne by consumers."  How about instead, humans stop factory farming meat and then we wouldn't infect and kill millions of innocent animals?  The real cost here is obviously the millions of dead animals.  There is nothing worse we could do to our environment than factory farm meat, this process should be illegal and it is unconscionable that the inhumane and environmentally deadly process continues.  

Cathy Golden
Cathy Golden

NG, you're kidding with the romantic photo of the lone pig on the hilltop at dawn, right? If only pork were produced that way in reality. If the cause of nationwide high prices and losses to the industry is imported feed as suggested, doesn't this suggest a lot of things we don't want to hear about how most of our food is produced? I expected more from NG. And I've read the May 2014 cover story. It, too, is pablum. At the least you could have used, for this posting, a photo of one of the industrial hog farms where the virus is a reality - which is the real story about why the outbreak has taken hold "industry"-wide in the first place.

Irfan Ahmed
Irfan Ahmed

In my opinion the agricultural habits of the farmers in todays day and age needs to become more humane. They need to learn how to develop sustainable farming so it the consequences of their habits don't have a detrimental impact on people. Simply put, this PEDv problem has now had a detrimental impact on the american economy as well as posing a risk to human health potentially. 

I am sceptical that researchers say it cannot be ruled out that the virus cannot be transmitted to humans. 

Margaret Swaid
Margaret Swaid

Um and you forgot to mention the part about how they immunize pigs....two ways really.  Grinding up the baby pig intestines and feeling to mom and dad pig OR simply feeding them diarrhea from infected pigs.


Hilda Roberts
Hilda Roberts

Your article reads:  "some speculate it may have been carried by dried blood added to pig food as a protein supplement...", this reminds me of the mad cow disease which may have been transmitted by feeding the animals meat and bone meal remains of other cattle infected by the disease.  Feeding our farm animals remains of other animals appears to be dangerous.  

Josh Mason
Josh Mason

Yet another reason to validate "Meatless Mondays", saying "no" to pork entirely (industrial farmed pigs are subjected to heartlessly cruel and disturbingly sad existences for their entire lives -, or better yet giving up meat in the 21st century so perhaps your grandchildren are left with a still habitable planet in the 22nd century.

dylan mueller
dylan mueller

donn clark you have absolutely no clue what you are talking about farmers have been changing many ways in there practices from breeding to market you guys think its so cruel to put a sow in a smaller crate so they can only move backwards we have went to the crates that the sow can get out and in as it pleases but they all lay there with there young and don't get out anyways and i have a few pigs around and in the barns they can move around and run around in there pens and move as needed. so there is another false statement.

Donn Clark
Donn Clark

As Mr. Forrest Gump said, "Stupid is as Stupid does", and our industrialized agricultural system (led by the beyond stupid Department of Agriculture) is stupid beyond comprehension. It takes less IQ than a fence post possesses to comprehend that placing 100,000 to 1,000,000 + pigs in tight quarters so they can't turn around is going to make any disease that hasn't been medically isolated (don't get me started on what is in that meat because of these practices) is going to pass from pig to pig easily, and spread through an entire population exponentially. 

. . . and the Department of Agriculture hires "educated" individuals? I think not!

Marty Hawkins
Marty Hawkins

People are still getting Asian wild boars into this country for hunting and breeding stock for are feral hog population. There is already a feral hog out break in this country.

Cindy Rose
Cindy Rose

Another great reason to avoid factory-farmed animals. Producers won't ever change the way they raise animals, even when diseases that are exacerbated by factory farm conditions strike down 10% of the pig population of this country. Disgusting.

Garry Asmus
Garry Asmus

@John Ibalio Bumagat

Please Tell us everything You know about immunization against the virus. All the farmers I know have been told by their vet that no immunization against  this virus has been aprove for use in the United States! I am sure there are thousands of Farmers that would like to know what you know!

amanda gensel
amanda gensel

@dylan mueller Can't agree more, I laugh and laugh when people go off about the sow being contained.  They can get up and walk away, the fact that they are too lazy to do so is no fault of the pig farmer.  The pen is designed only to keep the sow from killing her own offspring.  Something they manage to do with surprising impunity. 

amanda gensel
amanda gensel

@Donn Clark As a UMass grad and holding a Bachelors of Science in Animal Sciences I would like to see you pass the Department of Agricultures employment tests.  It is not about IQ but about having in depth knowledge of that aspect of agriculture.  Pig farms are some of the most bio secure farms on the planet to prevent disease from even getting on the property and protect the animals.  That is what makes such monster viruses like this one so dangerous.  One slip and you can lose every piglet on the property for months.  IQ is an antiquated way of proving impractical intelligence rather than the real world wisdom that farming requires.  And the average pig farm doesn't have 100,000 animals on it much less one million.

dylan mueller
dylan mueller

@Cindy Rose  many no such thing as a factory farmed animal. they may have many pens, building/units but that doesn't matter as long as they are comfortable have feed and water there is nothing wrong farmers change feeding bedding down pens building in so many ways you clearly do not have a ag background and the way you people that don't know much about this or have ever worked daily with these type of animals you have no say what is disgusting is the way you guys say things about farmers maybe you should look up "Paul harvey god made a farmer" that should maybe help you pea size brain out that you are obviously unknowledgable about livestock.


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