The 2013 wheat harvest season will soon be upon us, and soon thereafter, the late summer application of manure on the harvested fields will follow. The risk of spreading Porcine Epidemic Diarrhea (PED) through manure application should be a concern for all farms with pigs exhibiting clinical signs of the disease. PED is spread through oral-fecal contact, manure contaminated boots, clothing, birds and wildlife, transport trailers and other equipment.
Porcine Epidemic Diarrhea is a viral enteric swine disease with these clinical symptoms: diarrhea, fever, vomiting, and death (age dependent). These symptoms are indistinguishable from transmissible gastroenteritis (TGE). According to the Kansas State University, 2013 and Iowa Pork Industry Center TGE and PED are related in that they are both coronaviruses but cross immunity is not provided with infection of either virus.
As of the first of July the disease had been confirmed in more than 200 swine herds in the United States. Spread of the virus continues, and it is both a good animal husbandry practice and a good neighbor policy for all pork farmers with pigs exhibiting clinical signs of PED to obtain a confirmed diagnosis and immediately establish enhanced biosecurity practices to avoid spreading the virus within their own animals and (or) to neighboring swine herds.
A review of literature does not uncover any articles that discuss PED’s virulence in stored and spread manure. Because of PED’s similarities to the TGE virus recommendations for control of disease spread may best be based on practices for controlling TGE.
While viruses in general are rather short lived outside of the host animal Michigan State University Extension warns producers there is some risk of PED spread during manure pumping, transport and application. “Inactivation of viruses in liquid manure” reported that the TGE virus stays virulent more than 8 weeks in stored manure at 40 degrees F and up to 2 weeks in manure at 70 F. Therefore during the summer it is best to avoid hauling manure from pits under barns housing infected pigs for a minimum of 14 days after the animals have stopped showing clinical signs of PED. Assuming stored manure is near 70 F in the summer, 14 days will minimize the virulence of the PED virus in the manure. As the weather and manure cool, the time gap between pigs showing symptoms and manure hauling will need to be extended.
If manure must be removed from barns housing infected pigs, enhanced biosecurity practices are warranted, including:
- Clean, disinfect and dry manure pumping and application equipment – including tractor cabs – when moving between farms and farm sites. Effective PED disinfectants include Clorox, Virkon S, Tek-Trol and 1-Stroke Environ. The greatest risk of PED spread associated with manure spreading may be on manure application equipment when moving from infected barns to uninfected barns.
- All employees (both employees on the farm and custom applicators) working with manure application equipment should change into clean cloths and clean and disinfect footwear when moving between farms and farm sites.
- Custom manure applicators (CMA) should not be allowed access to pigs or to barn entry. Ensure the CMA has a phone number to reach you with questions.
- Employees and producers handling manure should shower and change into clean clothes and footwear, prior to accessing pigs.
- During field application, fully cover manure with soil by managing injection equipment and application rates to avoid manure boiling up in the injection slot and leaking on headlands. This will limit the possible transfer of the disease by birds and wildlife. According to a Kansas State University factsheet, there is also a possibility of short distant PED aerosol transfer.
Farmers using the services of custom applicators are advised to insist the applicators follow the first three points listed above.
PED will most likely continue to move through the United State’s swine herd. Improved biosecurity practices while handling manure will help limit the spread of the disease.