In Europe, the African swine fever virus (ASFV) has spread from the Caucasus region into Eastern Europe, and national authorities and the swine industries in Central and Western Europe are implementing measures to prevent its further spread.
Hog-dense Denmark was reported to be considering building a fence along its border with Germany to prevent potentially infected feral hogs from entering the country. (According to the World Organization for Animal Health, ASFV has not yet been detected in Germany, but it has been detected in wild pigs in eastern Poland, Latvia, Ukraine and Russia.)
If ASFV reaches the U.S., it could cause more than $16.8 billion in economic losses to swine and other industries, according to Kansas State University, and it would devastate trade and international markets.
Megan Niederwerder, assistant professor of diagnostic medicine and pathobiology in the Kansas State College of Veterinary Medicine, wants to prevent that. Her latest research has found that ASFV could survive in a simulated feed shipment across the ocean, which suggests that feed may be a potential way that pathogens may spread internationally.
The research appears in the journal PLOS ONE in the collaborative publication "Survival of Viral Pathogens in Animal Feed Ingredients under Transboundary Shipping Models." It is the first publication demonstrating the survival of ASFV in feed ingredients.
"The ultimate goal of our research is to understand what mitigation tools may be utilized to reduce the risk of (ASFV) being introduced, whether in the country of origin or once feed arrives in the U.S.," Niederwerder said.
There is no vaccine or cure for ASFV, which causes hemorrhagic fever and high mortality in pigs. It does not infect humans.
Niederwerder is collaborating with Kansas State University's Biosecurity Research Institute to continue studying the risk of ASFV in feed and feed ingredients. She is studying the whole swine feed transport cycle — from the shipment of feed as it is imported into the U.S. to when swine consume the feed on the farm.
"This research is extremely important to the swine industry not only in Kansas and the U.S. but also around the world," Niederwerder said. "There are many countries, including the U.S., that are currently free of ASFV, and it is critical to understand how we prevent this virus from being introduced. Through this research, we seek to understand and further define the risk of ASFV transmission when consumed in feed — a recently identified risk factor for the introduction of swine pathogens."
African swine fever is one of the diseases slated to be researched at the National Bio & Agro-defense Facility, which is under construction adjacent to Kansas State University's Manhattan, Kan., campus. Niederwerder's work at the Biosecurity Research Institute will provide the foundational knowledge that can then transition into further studies at the new agro-defense facility once it is fully functional.
Niederwerder's research is organized into three parts: (1) understanding if the virus survives in feed ingredients using a transboundary model that simulates the shipment of feed from other countries into the U.S.; (2) determining the oral dose of ASFV necessary in feed to cause infection, and (3) Identifying mitigants that reduce or eliminate the risk of ASFV transmission in feed ingredients, including any additives that may inactivate the virus in swine feed.
Niederwerder and her team are performing the research in a Bio-Safety Level-3 laboratory at the Biosecurity Research Institute. They have been studying complete feed and feed ingredients in 5 g amounts, including soybean meal, lysine, dried distillers grains, choline, vitamin D and others.
Researchers place the ingredients in 50 mL tubes in an environmental chamber and use meteorological data to program the chamber's temperature and humidity to mimic a cargo ship's journey from Eastern Europe to North America. For example, the transatlantic model that simulates travel from Eastern Europe takes 30 days.
The researchers then study if the virus is still present at a dose infectious to pigs after the simulated shipment and if there are any additives that may stop the virus from spreading through feed.
"Our aim is to understand if we can mitigate this risk and protect the U.S. swine industry from the introduction of African swine fever as well as other foreign animal diseases," Niederwerder said.
To support this research, she has been awarded more than $700,000 from the state of Kansas National Bio & Agro-defense Facility Fund, the National Pork Board and the Swine Health Information Center. Niederwerder recently presented this research at the North American PRRS symposium, the American Association of Swine Veterinarians annual meeting and the Midwest Animal Science meeting.
Other Kansas State collaborators on this work include Raymond "Bob" Rowland, professor of diagnostic medicine and pathobiology; Cassie Jones, associate professor of animal sciences and industry; Steve Dritz, professor of diagnostic medicine and pathobiology; Trevor Hefley, assistant professor of statistics; Jason Woodworth, research associate professor of animal sciences and industry, and Mike Tokach, university distinguished professor of animal sciences and industry. Scott Dee of Pipestone Veterinary Services and Diego Diel of South Dakota State University are also collaborators.