DES MOINES – Porcine Epidemic Diarrhea Virus (PEDv) can survive in manure for at least four months, according to interim research results from work conducted at the Swine Veterinary Center, St. Peter, Minn. The Pork Checkoff funded the project.
Research shows that PEDv is capable of surviving at least 14 days at 25°Celsius, and greater than 28 days when stored at 20° and 4°C.
"With this in mind, little is known about the duration of which manure from field settings is able to retain viable PED and therefore making informed decisions regarding how to sequence pumping crews and risks of applying infective manure is challenging," researchers wrote.
So, researchers designed a pilot project to achieve two objectives:
• Improve understanding of the risks posed by manure in pits transported and applied to fields, as well as risks to negative pigs entering potentially contaminated grow finish sites using samples from field infections rather than spiked samples from the lab.
• By sampling a large cross section of farms at six and four months post infection, it may be possible to detect associations between bio assay positive (or negative) pit status and variables we intend to measure for each barn and pit
Researchers sampled manure from barns that were either filled with known PEDV positive pigs or that had confirmed lateral infection. For the study, researchers selected 15 barns approximately six months post infection and 15 barns approximately four months post infection.
Manure was sampled through pit pump out using a 10-ft. length of PVC pipe angled into the pit under the pigs as far as collection personnel could reach.
Preliminary results show that 14 of the 15, six-month post infected barns tested positive by PCR. But none of the positive samples tested positive for live virus by swine bio assay. In the four month post infection barns, 13 of the 15 barns tested positive by PCR. Of that number, two tested positive for live virus by bio assay.
Researchers concluded that there could be potentially less live virus in manure pits than originally suspected. However, 15 percent of the barns tested by bio-assay tested positive for live virus.
"Specifically, the researchers advocate that producers start any manure pump-out procedures from sites that haven’t had an outbreak first, followed by barns with the longest time post-PEDV infection all the way to ones with the most recent PEDV infection last," the Pork Board said in its latest PEDv update. "This is the same protocol often advised for manure from herds with other diseases such as Porcine Respiratory and Reproductive Syndrome (PRRS)."
The project is ongoing as researchers try to understand factors that favored the survivability of the positive samples in the four month post infection barns. The Pork Checkoff-funded project is led by Steve Tousignant, a veterinarian and epidemiologist at the Swine Veterinary Center.