A recent outbreak of porcine epidemic diarrhea virus in Canada had officials looking at possible sources, including porcine plasma protein, a common feed ingredient in early weaning diets, says Steve Dritz, Kansas State swine veterinarian.
The viral disease is caused by a porcine coronavirus and can take a major toll on a swine operation, K-State's College of Veterinary Medicine says. The disease can spread quickly and can eventually lead to severe sickness and death.
"The disease is a new introduction into the United States, so we have a population of pigs that are highly susceptible," Dritz says.
Part of Canada's investigation includes dried plasma, a feed ingredient that is used as a protein source for early weaned pigs.
It's often made from cattle or pig blood that is collected at slaughter facilities throughout the United States. The plasma is separated from the blood and goes through a drying process before being shipped as a feed ingredient. The product provides many nutritional benefits to young pigs at weaning, as it enhances growth rate and feed intake, K-State says.
In the recent investigation in Canada, the presence of the virus in the porcine plasma protein was identified by a polymerase chain reaction test, a highly sensitive test that measures genetic material, Dritz said.
The test can determine the existence of the virus, which theoretically could be inactive, and therefore, not be infective. In this case, it could be fed to pigs and not cause them to become ill.
"The products go through processes that should inactivate the virus, but similar to salmonella with some feed ingredients, you get cross-contamination, for instance, if a truck that was contaminated touches the product," Dritz said. "We're seeing suppliers of these types of ingredients starting to reexamine their processes. We think a majority of these ingredients are probably not infective, but there may be some that are."
In addition to looking closer at potential cross-contamination and feed ingredient processing, the investigators in Canada also took the next step of taking a potentially infectious porcine plasma protein product and feeding it to susceptible pigs, he said. Those pigs reproduced the disease, which provided strong evidence to link transmission through feed.
Canada reports latest findings
The Canadian Food Inspection Agency reported the results of its latest tests March 3, finding that it cannot confirm a link between feed containing blood plasma and Porcine Epidemic Diarrhea virus cases in Canada.
CFIA confirmed that the bioassay study demonstrated that the porcine blood plasma in question contained PED virus capable of causing disease in pigs. However, the study could not demonstrate that the feed pellets containing the blood plasma were capable of causing disease.
Options for U.S. producers
"We're trying to help producers by providing them with nutritional options," Dritz said. "Many in the industry have decided that this is a potential route of transmission and want to eliminate the route as a risk. So, many swine producers are eliminating porcine protein sources out of sow farms and diets for baby pigs."
Dritz said a lot has been learned from the Canadian case, but there are many questions yet to be answered. While researchers address the questions, producers should be familiar with their feed ingredients and do a risk assessment for their potential as a route of disease transmission.
"We see our role as providing information and options, and we're working to figure out research questions and get research initiated to find answers," Dritz said.
The National Pork Board reports that although the virus can be deadly to young, susceptible pigs, it is not zoonotic. It poses no risk to other animals or humans, nor does it affect the safety of pork products.
News Source: K-State