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PEDv Dominates the Pig World

While there were hundreds of things to see, do, and talk about at the 2014 World Pork Expo (WPX) this summer in Des Moines, Iowa, only one subject trumped everything else: porcine epidemic diarrhea virus, or PED.

A year ago at WPX, PED was a blip that had most pork producers’ attention, but no one could foresee just how quickly it would spread to infect half of all the sows in the U.S. No one knew how destructive it would be in pig farrowing houses. Painfully, we know now. Here are some of the highlights and comments from a variety of pork sources.

7 million dead piglets

PED infects the sows, who typically pass the virus to their piglets through manure and nose-to-nose contact. If the sows have no previous exposure, they are unable to impart immunity to pigs through their colostrum. The virus unabatedly destroys the lining of the pigs’ gut, causing severe diarrhea and dehydration. 

For newborn piglets, that’s almost always deadly. Howard Hill, president of the National Pork Producers Council, says estimates from Minnesota are that half of the U.S. sow herd has been infected in the last year alone. With 6 million sows, that means 3 million have had PED. While some sows lose 100% of their piglets, others survive. On average, the loss is 2.7 pigs per sow per year. Multiply that out, and the loss to PED is about 7 million piglets, or 10% of the pig crop, in the past year. About 1.3 million pigs died from PED in January 2014 alone. “We can make up for some of the loss by better performance of the ones that survive or less of other diseases,” says Hill. “We can feed the survivors to heavier weights to make up for some of the tonnage loss.”

Good news

It’s slowing down. There is good news about PED: There have been fewer reported occurrences of the disease in recent weeks. Like many viral diseases, incidence is always higher in the winter months – viruses thrive on cold. “The fact that the number of cases is declining now is good news,” says Tom Burkgren, a veterinarian with the American Association of Swine Veterinarians. “What we don’t know is if it will pick back up again when we return to cold weather. On some farms, just when you think you got through a PED outbreak and can relax, mortality goes back up again eight to nine weeks later. We’ve got some herds that have been fighting a PED infection since January.” 

We know that getting immunity in an entire sow herd is important, he continues. “We’ve seen herds where the pigs from one sow will be OK, but the crate right next to her will have a 30% loss of pigs. We have to get all the sows immune and do good cleanup between farrowing groups. We may have to clean the farrowing pens better and let a farrowing room dry out and sit empty longer between groups of sows.”

Vaccines coming 

There is one on the market (Harris Vaccines), and more are in development and could be available by fall of 2014, says Burkgren. They are still in testing stage, and they are showing moderate success. However, they are not the total or final answer. The best answer now is controlled exposure of sows to the live virus to build herd immunity, then controlled traffic onto each farm and barn, and excellent biosecurity measures.

Like nothing before

Burkgren says one estimate he has seen shows just how concentrated and virulent the PED virus is: If you took 1 gram of PED-infected pig feces (about the size of the eraser on a pencil) and diluted it in 24,000 gallons of water, then gave that water to pigs, it would still make them sick. “We haven’t seen anything like this one before,” he says. Still, he says, there is no food safety issue or human health issue associated with PED.

China connection? 

The best guess is that this virus somehow found its way to North America from China. “We can only speculate about this,” says NPPC chief veterinarian Liz Wagstrom. “The genetic makeup of the virus is of Chinese origin. There is just so much traffic from China with all the trade we do with them, it’s easy to see how it could happen.” There are two strains of PED seen in the U.S., and neither evolved here, she says.

How much is it costing us? 

If PED kills 7 million baby pigs, the loss is the margin those pigs would have profited over variable costs, says Dale Polson, a veterinarian for Boehringer Ingelheim Vetmedica. If you put that number at as little as $50 per pig, the industry loss is at least $350 million.

How it feels to a farmer

Jay Gruber is the production manager for Northwind Pork in Indiana. Northwind has three sow farms totaling 6,500 sows, and all three have been through PED since last November. 

“With the first farm, I got a call on a Sunday afternoon that the pigs in one farrowing room had loose stools,” Gruber says. 

“By the very next day, it was in 20 rooms. For about two weeks, we lost just about every pig born. If they were one or two days old, they died within a day or two from dehydration. The older pigs lingered longer, and some of them lived through it,” Gruber says. 

By the end of two weeks, Gruber had exposed sows in gestation to the virus, and those sows were able to pass immunity to the pigs. The losses slowed, and then they stopped. 

On the second and third Northwind farms to contract PED, Gruber says they had learned how to control exposure and get immunity in the sows. Pig losses were not nearly as severe. 

“With each outbreak, we got better,” he says. “I think the lesson is that you can contract PED and get through it.”

Many unknowns 

There was a report recently that a farm in Indiana rebroke with a bout of PED after it was thought that all sows had acquired immunity in the first outbreak. 

“We really don’t know enough about PED to say for sure what is happening on PED farms,” says Dane Goede, a University of Minnesota veterinary graduate student who studies the incidence of the disease.

“I can’t say that I’m surprised that PED would come back a second time on a farm,” Goede says. “We don’t know enough to say if it is a rebreak on that farm. Or it may be that the first break never really went away. This disease hits each farm differently. On some, immunity builds, and PED goes away. On others, it lingers. 

“At this point, we just don’t know what makes the difference,” he says. 

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