Spray Dried Porcine Blood Products Are Safe Porcine Epidemic Diarrhea Virus

CANADA - Pig herds infected with Porcine Epidemic Diarrhoea (PED) have been confirmed in Ontario and suspected in two more provinces, while a feed product based on porcine plasma produced in the US has been found to carry the PED virus. PEDv infected herds are confirmed in Ontario and suspected in Manitoba and Prince Edward Island, according to the American Association of Swine Veterinarians (AASV). The Canadian Food Inspection Agency (CFIA) reports a positive bioassay resulting from exposure to samples of US-origin plasma product. Testing has determined that PED virus was present in samples of US-origin plasma obtained at the third-party manufacturer for Grand Valley Fortifiers. This plasma was used as an ingredient in feed pellets produced by the company. Testing with a swine bioassay has determined that the plasma ingredient contains PED virus capable of causing disease in pigs.

It is my understanding that PCR testing has determined the presence of the PED virus, however, these tests cannot distinguish between infectious virus cells and dead virus cells. The bioassay results are stated as preliminary and antibody tests are still in process. If you have official information that a controlled test has proven that piglets fed plasma or other items which have tested positive for the presence of PED virus (again, without being able to distinguish between infectious and dead virus cells) have resulted in those piglets having contracted infections PEDv please post the location of that information.

http://www.inspection.gc.ca/animals/terrestrial-animals/diseases/other-diseases/ped/2014-02-18/eng/1392762739620/1392762820068 CFIA Statement on Porcine Epidemic Diarrhea Virus in Feed February 18, 2014: The Canadian Food Inspection Agency (CFIA) is conducting science-based testing to determine if feed may be a contributing factor in the current Porcine Epidemic Diarrhea virus (PEDv) situation. PED poses no risk to human health or food safety. Proper biosecurity measures remain the first and best line of defense for pork producers to protect against PED. As a precautionary measure, on February 9, 2014, Grand Valley Fortifiers issued a voluntary recall for certain pelleted swine nursery feed products containing porcine plasma. Testing has determined that PED virus was present in samples of US-origin plasma obtained at the third-party manufacturer for Grand Valley Fortifiers. This plasma was used as an ingredient in feed pellets produced by the company. Testing with a swine bioassay has determined that the plasma ingredient contains PED virus capable of causing disease in pigs. Further testing will be done to assess if the feed pellets are capable of causing disease in piglets, and results are expected within days. Testing will continue to confirm a direct link between the feed and the spread of the disease, as the virus is only confirmed in a single ingredient at this time. The CFIA is working closely with the company to confirm the effectiveness of the recall, and is closely examining company records to see where potentially affected product was distributed. The CFIA is also reviewing records of other imports of swine plasma and will work with the Council of Chief Veterinary Officers and the pork industry in Canada to proactively manage the possible risk of transmission through feed. As the investigation continues, additional actions such as recalls may be necessary to minimize the potential that feed could contribute to the transmission of this disease in Canada.

When will CFIA complete and make public test results which determine if pelleted feed contains infectious virus cells or simply dead virus cells (which show up on PCR tests, leading to statements that these feeds test positive for the PED virus without making a distinction between living (infectious) and dead cells?

The University of Minnesota has published a report of a bioassay to evaluate the infectiousness of feed samples that had tested positive for PED virus by PCR alongside a control group inoculated with three different dilutions of PEDV- positive material obtained from clinical cases submitted to the Minnesota VDL. The report summarizes as follows: "We were able to reproduce Porcine Epidemic Diarrhea (PED) by oral and intragastric administration of PCR-positive fecal material from PED clinical cases. However, PED was not reproduced in pigs inoculated with feed samples that were positive for PEDV genetic material by PCR. The results from this bioassay indicate that feed can contain PEDV genetic material that is detectable by PCR but is not infectious." The full report can be found at http://www.cvm.umn.edu/sdec/prod/groups/cvm/@pub/@cvm/@sdec/documents/content/cvm_content_447842.pdf Further, the Swine Health Monitoring Project (apparently involving the USDA) fed four PED PCR positive pig feed samples from two different sources to test viability in a bioassay. The report states "None of the samples tested positive for live PED virus. This conclusion is based on lack of visible severe diarrhea (sporadic, mild diarrhea was observed), no significant decrease in Ct values from inocula (via 1 sample t-test) and no evidence of infection on samples collected at necropsy (PCR and IHC negative." The full report can be found at http://www.cvm.umn.edu/sdec/prod/groups/cvm/@pub/@cvm/@sdec/documents/content/cvm_content_472291.pdf Why isn't this information getting out there?

I agree that the PCR test determines presence, but not viability, of PEDv. However, NPPC at the recent PISC conference stated that PEDv is difficult to grow in the lab. From my experience, I would guess that this is true (growing viruses is difficult). Doesn't this increase uncertainty in the transmission route? Couldn't you have a viable but nonculturable situation?

I don't think the question is one of whether or not one can grow the virus in the lab. The problem seems to be that some have pointed the finger at feeds which have tested PCR positive for the presence of virus, but the bioassay results demonstrate that the cells seen in these feed ingredients are not infectious. Some normally smart people are talking about continued PCR testing as a litmus test for the suitability of feed ingredients with the result being that some feed ingredients (which test PCR positive, but do not contain infectious cells) may be excluded from the feed. Many of these feed ingredients are helpful to piglets in that they help the digestive system mature faster and healthier and so excluding them could be unhelpful. Beware unintended consequences...

Hi Michael, I agree with all of your comments, but you state "the bioassay results demonstrate that the cells seen in these feed ingredients are not infectious." How can this be known if PEDv is difficult to culture? Wouldn't an improved bioassay involve the use of piglets (I realize this would not be cheap or easy, but with all of the uncertainly surrounding PEDv, may be warranted)? Thank you.

Dave, thanks for keeping this thread going. The University of Minnesota and the USDA Swine Health Monitoring Project both did feeding trials where they fed a control group feed which was inoculated with live virus and the test group which used feed which had tested PCR positive. The control group all got PEDv and the test group did not, thus they each concluded that the PCR positive feed samples did not contain infectious virus. These tests were done independently.

Thank you for your comments, too. Interesting study. I've read that transportation (trailers, trucks, etc.) is also being examined. This poses a difficult situation, however - has anyone taken samples from trailers or trucks with PEDv pigs and fed those samples to piglets to see if they develop PEDv? It seems like we're in the same situation here - sure, the trailers test positive, but according to our conversation here, those results are likely meaningless. It really comes back to good management and cleaning, and IMHO, should happen now. We shouldn't be waiting for a vaccine; this is a crutch. Good management practices should ALWAYS be part of the SOP.

From what I have read I do believe there may be significant exposure to PEDv environmentally. Let me be clear, though, that this is likely not the same as with these feed ingredients as PED cells seen environmentally have not undergone the heat treatment common to feeds (which is what inactivates the virus). Good sanitation SOPs are critical.