Since its initial detection in May of 2013, porcine epidemic diarrhea virus (PEDv) has spread rapidly throughout the U.S. swine industry, killing millions of piglets. Initially, contaminated feed was proposed as a risk factor for PEDv; however, data were not available to support this theory.
Just released research conducted by Pipestone Veterinary Services and South Dakota State University (SDSTATE), now confirms that feed can be a carrier of the virus. The work was reported in BMC Veterinary Research.
For on-farm detection of PEDv RNA in feed, paint rollers were used to collect material from at-risk feed bins from three clinically affected breeding herds. The material was tested by PCR and determined to be positive for PEDv-RNA (Ct = 19.50-22.20 range).
To test infectivity, the material was pooled (Ct = 20.65) and a treatment group of three-week-old PEDv-naïve piglets were allowed to consume it via natural feeding behavior.
For the purpose of a Positive control, piglets were allowed to ingest feed spiked with stock PEDv (Ct = 18.23) while the negative control group received PEDv-free feed. Clinical signs of PEDv infection (vomiting and diarrhea) and viral shedding were observed in both the Positive control and Treatment group’ post-consumption with virus and microscopic lesions detected in intestinal samples. No evidence of infection was observed in the Negative controls, according to researchers Scott Dee, Adam Schelkopf and Joel Nerem of Pipestone Applied Research, Pipestone Veterinary Services, and Travis Clement, David Knudsen, Jane Christopher-Hennings and Eric Nelson of the Animal Disease Research and Diagnostic Laboratory at SDSTATE.
The researchers said “these data provide proof of concept that contaminated complete feed can serve as a vehicle for PEDv infection of naïve pigs using natural feeding behavior.”
In response to the finding, the Richard Sellers, senior vice president of the American Feed Industry Assn. (AFIA) said it is important to note that being a carrier of the virus does not mean that feed is the source of the virus. He said the prevalence of the disease on an infected farm can contaminate many items."There are still many unknowns related to the outbreak of the virus, and AFIA's goal is to work with industry partners, swine producers, veterinarians and the government to conduct and evaluate research to better understand the cause and transmission routes of PEDv,” said Sellers. As a step to find answers, AFIA and industry partner, the Institute for Feed Education & Research, pledged $100,000 to the National Pork Board in May of this year.