A new virus, identified and isolated in May 2013, has been wreaking havoc on pig growers and as we go into our new piglet season, I thought I’d take some time to explain Porcine Epidemic Diarrhea Virus (PEDv). PEDv is a corona virus similar to Transmissible Gastroenteritis (TGE) another terrible cause of piglet death. We know that PEDv is spread through fecal contamination and if manure is dried and airborne, aerosolized transmission is possible. Corona viruses are named because they show a halo around them under an electron microscope. That halo is what virologists call an envelope. The good news is that enveloped viruses are much less likely to survive in a clean environment because the envelope deteriorates rapidly. The bad news is that PEDv seems so infectious that it doesn’t have to last long in the environment to infect the next pig.
What does this all mean for our small producers? So far the recommendations for prevention of transmission are to avoid other pigs, avoid transporting with other pigs, keep birds away from pigs, and practice biosecurity. That’s all well and good for large hog farms with indoor housing and multiple trucks for transportation, but what’s a small diversified farm to do? Birds transmit TGE and PEDv and birds are a fact of life on a farm. I think re-creating Silent Spring in response to a virus is a bit of an overreaction. A qualitative risk analysis is in order and then some concrete steps to take to reduce risk and deal with the hazard of PEDv is a good place to start.
First, the danger of PEDv is that it infects all stages of pigs causing explosive diarrhea and has 100% mortality in preweaned pigs. Farmers experience high costs to treat as well as loss of productive pigs while older pigs recover from the dehydration and electrolyte loss. It’s very expensive to treat a pig that’s not putting on weight for market.
What’s the risk of your operation?
So what farms are at risk? Right now, this virus has been identified at large hog operations, but, that’s where the vets and research money are. Smaller producers who can’t or don’t implement practices are at very high risk. The highest risk small producers would be ones who are close to large hog operations. If there are birds coming in and out of the tractor trailers parked outside, those birds are flying to other farms. Other at risk small producers are ones who buy at auction and bring piglets back to the farm to grow. Lower risk producers would be farms that produce all replacement gilts in house and take finishers to slaughter themselves. Also lower risk would be farmers with low stocking densities that prevents high concentrations of the virus in any one spot if a pig gets sick. Many diversified farmers fall along a spectrum of risk with their practices.
So what can small hog producers do? First off, don’t feed garbage, pigs or pig waste to your pigs. If you have a pig that dies of explosive diarrhea, incinerate it. Do not compost it and don’t grind it into food for the pigs. While yes, it is legal to grind up piglets from your own farm and feed it to sows, it’s a terrible idea for a lot of reasons. Remember any off farm meat or garbage that is fed to pigs must be cooked first and there is permitting and inspection that goes along with a garbage cooker. Garbage in, garbage out and disease transmission to boot. Don’t do it. Expose the sows to the diarrhea, because that’s where the viral load is.
Second, practice biosecurity. Do not let vehicles that go on other farms with pigs onto your farm. If they must come on, such as your veterinarian’s truck, make sure the truck is disinfected first. Spray wheels and bumpers. Make sure personnel wear clean booties and coveralls. Wash hands. If you must clean up the barn, do not put the hose on high and blast the diarrhea off the walls, because you’ll be aerosolizing it at the same time. If it is on the floors, you can spread clay cat litter down to absorb moisture and shovel up the remains. Then, use low pressure water and a mop or squeegee to clean the floor of the barn. Then, once all organic material is up from the surfaces, you can disinfect it with sodium carbonate (washing soda) and iodine based disinfectants.
Third, if your herd is affected, repopulate from a negative herd. But before you repopulate, let the virus blow through your herd. While a vaccine is in the works, natural immunity is going to have to play a part. Isolate any new animals for three weeks before your house them with your herd.
Viruses in pigs are complex and they cause a lot of heartache to producers. But, being aware of new diseases that are in the pig population and practicing good biosecurity and hygiene can go a long way to reducing the risk of PEDv.
Thanks to Dr. David Reeves at the UGA College of Veterinary Medicine for his help on this article.
If you would like to discuss the topic of this post with Dr. HACCP and others, please do so on The Salt Cured Pig’s Facebook Group.