Feed quality

A study conducted by veterinary researchers at Kansas State University sheds new light on a threatening swine disease: African swine fever.

The research team, headed by Megan Niederwerder, assistant professor of diagnostic medicine and pathobiology in the College of Veterinary Medicine, looks at the degradation of African swine fever virus in animal feed ingredients to understand the potential for disease spread, according to a Kansas State news release.

Up to now, data has been limited. Niederwerder’s latest study examines the possible risk of African swine fever virus spreading to the United States through imported feed.

The study provides more accurate half-life measurements that confirm the virus can survive a simulated 30-day transoceanic voyage in contaminated plant-based feed and ingredients.

“This study provides additional evidence supporting the potential risk that feed may play in the transboundary movement of African swine fever,” Niederwerder said.

Detailed analysis shows the half-life of African swine fever virus in feed ranges from 9.6 to 14.2 days after exposure to varying temperature and humidity conditions simulating transoceanic shipment. This means it would take approximately two weeks for the total viable virus concentration to decay by half its original count under the conditions of a transatlantic voyage.

The new study expands on Niederwerder’s previous work confirming the likelihood of African swine fever transmission through feed and can be used to implement science-based management practices such as storage time to reduce this risk.

“Transmission of swine viruses through feed has been recognized as a risk since around 2013, but the probability of African swine fever virus infection through plant-based feed was unknown until our publication earlier this year,” Niederwerder said.

Over the last year, African swine fever virus has emerged on new continents and spread to historically negative countries. If the virus can survive shipments overseas, this provides an opportunity to infect swine in the United States and other countries through imported feed.

“The emerging threat of African swine fever virus being introduced into the United States is staggering and significant efforts are focused on preventing entry,” Niederwerder said.

African swine fever is now considered endemic in China, where the world’s largest population of pigs live. Chinese production of pork is estimated to be cut by 25% by the end of the year. The disease has also spread to several other Asian countries and recently to Western Europe.