Tech + Health

08.20.14

Aporkalypse Now: Pig-Killing Virus Could Mean the End of Bacon

A virus called PEDv is killing 100,000 pigs and piglets each week, and shows no signs of stopping.

It’s a carnivore’s worst nightmare: A virus is sweeping through America’s hog farms, causing massive die-offs among piglets. Pork prices have spiked, rising 14 percent in the past year, due in large part to the 7 million casualties from the Porcine Epidemic Diarrhea virus (PEDv). With bacon retailing at $6.11 per pound in American cities, farmers and food lovers alike have begun to wonder if this could be the end of bacon.

The aporkalypse began last spring, when piglets on farms in Iowa began dying of severe diarrhea. At first, officials believed it was caused by the transmissible gastroenteritis virus, which has been known to cause significant outbreaks on U.S. farms. But measures to contain this virus weren’t working, and the U.S. Department of Agriculture began to look more closely. They found PEDv.

It’s alarming, says X.J. Meng, a virologist at the Virginia-Maryland College of Veterinary Medicine, because PEDv had never been seen in the U.S. before. “It’s not a new virus—it’s been around since the 1970s, but it’s new to the U.S.,” Meng said. “The Iowa and Minnesota strains are nearly identical to the Chinese [PEDv] virus,” Meng explains.

This makes case counts a little fuzzy, but most researchers estimate that 100,000 pigs and piglets are dying from PEDv each week. Since the outbreak began, more than 7 million have died.

Because of the initial attribution to a more mundane pathogen, scientists have been unable to track down exactly how the virus may have first arrived in this country. What’s happened since then, however, has been much easier to follow. In one year, PEDv has spread to more than 30 states, even during times when viruses similar to PEDv aren’t readily transmitted. Since no pigs are immune to PEDv, the virus has spread quickly, with high death rates in its path.

The USDA only required farmers to report the presence of PEDv in their herds this past June, more than a year after the virus first entered the U.S. This makes case counts a little fuzzy, but most researchers estimate that 100,000 pigs and piglets are dying from PEDv each week. Since the outbreak began, more than 7 million have died. The 5 percent drop in the U.S. hog herd from 2013 to 2014 (from 65.2 million pigs to 62.1 million) is nearly all attributable to PEDv. These declines have led to spikes in pork prices as well.

Although PEDv might not have a name that sends shivers up the spine quite like “Ebola” or “Marburg,” it has torn through the pig population like many scarier-sounding viruses do in humans. As its name suggests, PEDv causes serious diarrhea. It sounds like a fairly banal symptom—none of the bleeding out of every orifice and then some that physicians are seeing in the current Ebola outbreak. But diarrhea can and does kill in both humans and pigs. Older pigs may be sick for a few days, but they generally survive. Piglets, especially those under 10 days of age, aren’t so lucky. Without the reserves of their older cousins, piglets often don’t survive PEDv infections. Like many gastrointestinal viruses, PEDv is spread by the fecal-oral route, and it can also survive for long periods of time on inanimate objects and solid surfaces.

This last capability of the virus appears to be how the pathogen is spreading between farms in different states. Say a sick pig is loaded onto a transport vehicle, says Jim McGraw, Wisconsin’s state veterinarian. It can not only spread the virus to other pigs on that truck, but viable virus particles can remain on the truck when the next batch of pigs arrives. Then, those pigs go to their various destinations, taking the virus with them. “We haven’t yet identified every means of spread,” McGraw says.

A visit to your local pig farm now requires nearly as much preparation and gear as entering a CDC biocontainment zone.

To stop the spread of virus, farmers have had to become experts in biosecurity. Between runs, transport trucks not only must be cleaned, they now have to be sanitized. Any vehicles that arrive on a farmer’s property are hosed down with disinfectant. Feed origins are scrutinized. Farmers have begun limiting access to their farms and pigs to prevent virus importation. Anyone having contact with the animals must wear disposable suits and booties to prevent the spread of infections. A visit to your local pig farm now requires nearly as much preparation and gear as entering a CDC biocontainment zone.

Both Meng and McGraw say these are good practices for the industry to take, but it’s still not clear whether they’re having an effect on PEDv. Numbers of cases have gone down slightly this summer, but this tends to be a time when the virus is naturally less transmissible. The heat and humidity make it harder for PEDv to survive. Only as the weather gets colder will researchers know for sure whether their efforts were successful.

“It spread through last summer, and it’s spreading through this summer, so something is telling me that we still haven’t figured out why the virus is spreading like this,” Meng says.

Both farmers and researchers are hoping to develop a PEDv vaccine in the near future. An injectable, killed virus vaccine was just approved by the USDA, but it appears to be less than ideal. Still, farmers are using it because it’s better than nothing, although everyone is holding out hope than an oral, live virus vaccine will be developed soon. Both the USDA and the National Pork Board are funding research in this area.

McGraw emphasizes that there is no public health risk to humans from the virus, and that pork is safe to eat. Less clear is the virus’ impact on environmental conditions. For the past two years, retired Marine Corps officer Rick Dove has been photographing the hog industry in eastern North Carolina from a small plane and has accumulated nearly half a million photos. What he found shows that the PEDv outbreak may be worse than anyone suspected.

“We’ll look at their dumpsters and we’ll see these pigs just overflowing…Buzzards are all flying around pecking at them, and there are insects and flies, and you can see blood on the ground.”

“They do send some of the dead pigs off for rendering, but when we’re driving around, we’ll look at their dumpsters and we’ll see these pigs just overflowing. And these aren’t just little pigs; they’re also the big sows. Buzzards are all flying around pecking at them, and there are insects and flies, and you can see blood on the ground. It’s a very grotesque scene,” Dove says.

The large number of dead adult pigs Dove has spotted indicates that the low mortality among sows may not be the case, although he couldn’t determine the cause of death for these pigs. And with so many pigs dying, farms have been challenged to try to find hygienic ways to dispose of the carcasses. Improper burial, Dove says, could mean that harmful bacteria are leeching into the waterways. In eastern North Carolina, which has been hard hit by PEDv and contains many hog farms, the water table is extremely high, making it easy for contamination to occur.

“Pigs produce 10 times the fecal matter as humans. That means that all the pigs in North Carolina produce the same amount of feces every day as the people in North Carolina, California, New York, Texas, Pennsylvania, New Hampshire, and North Dakota,” Dove says.

Intensive livestock farming basically means housing animals in artificial cities. Just as humans needed to develop wastewater processing facilities to promote optimal health in our urban areas, we will need to do the same for livestock, Dove says.

“If we don’t fix this situation, PEDv isn’t going to be the worst thing that we’re going to see,” Dove says.