New research from the Kansas State University College of Veterinary Medicine investigated how feed and feed ingredients may play a role in the possible spread of two globally significant swine viruses.
Megan Niederwerder, lead researcher and Kansas State assistant professor of diagnostic medicine and pathobiology, and her colleagues published a report on classical swine fever (CSF) virus and pseudorabies virus stability in feed ingredients subjected to different environmental conditions mimicking transpacific shipment.
The paper, "Stability of Classical Swine Fever Virus & Pseudorabies Virus in Animal Feed Ingredients Exposed to Transpacific Shipping Conditions," is available online in the journal Transboundary & Emerging Diseases.
"Classical swine fever virus and pseudorabies virus cause two of the top four transboundary animal diseases of importance to swine," Niederwerder said. "Both viruses are endemic to areas of the world where feed ingredients are manufactured and imported into the United States each year."
Currently, U.S. commercial swine are free of both CSF virus and pseudorabies virus because of costly eradication programs completed in 1978 and 2004, respectively, Kansas State said. Niederwerder said reintroduction of these viruses into U.S. swine herds would be devastating, and there are concerns that feed ingredients incorporated into swine diets may serve as new vectors for the spread of animal disease.
Recent changes in pseudorabies virus strain virulence and the geographic distribution of CSF virus are also concerns, she added.
"The emerging threat of classical swine fever virus and pseudorabies virus being reintroduced into U.S. commercial swine is significant, and preventing entry is critical for the U.S. pork industry," Niederwerder said. "The route of introducing and transmitting swine viruses through feed has been recognized since the 2013-14 outbreak of porcine epidemic diarrhea virus. However, the stability of classical swine fever virus and pseudorabies virus in imported feed ingredients had yet to be investigated."
In the study, the researchers found that both viruses survived for the length of the 37-day model in feed, with pseudorabies virus having increased stability across a broader range of feed ingredients compared to CSF virus.
Niederwerder said pseudorabies virus was recovered in nine of the 12 tested ingredients: conventional and organic soybean meal, lysine, choline, vitamin D, moist cat food and dog food, dry dog food and pork sausage casings at the conclusion of the simulated voyage. For CSF virus, two of the 12 ingredients had infectious virus detected: conventional soybean meal and pork sausage casings.
"This study reports novel data about environmental stability of classical swine fever virus and pseudorabies virus in feed and includes important quantitative information that can be incorporated into risk models for preventing the potential spread of classical swine fever virus and pseudorabies virus through imported feed ingredients," Niederwerder said. "This information adds to our work on African swine fever and reinforces the concept of feed biosecurity for disease prevention."
This research was conducted at Kansas State University's Biosecurity Research Institute, a Bio-safety Level-3 and Bio-safety Level-3Ag facility that allows safe and secure research with animal and plant diseases foreign to the U.S., in collaboration with other university and industry contributors. Co-authors on the manuscript include Ana Stoian, Vlad Petrovan, Laura Constance, Matthew Olcha, Maureen Sheahan and Bob Rowland with Kansas State University; Scott Dee with Pipestone Veterinary Services; Diego Diel with Cornell University and Gil Patterson with Lincoln Memorial University.
Funding for this study was provided by the Swine Health Information Center and the State of Kansas National Bio & Agro-defense Facility Fund.