New information is being learned about how the currently circulating strain of African swine fever (ASF) could spread in feed and feed ingredients.
Researchers at Kansas State University’s (KSU’s) College of Veterinary Medicine say they have discovered the dose necessary to transmit the disease when pigs ingest virus-contaminated feed or liquid. They found the level of virus required to cause infection in liquid was extremely low, demonstrating the high infectivity of ASF through the oral route. The study—“Infectious dose of African swine fever virus when consumed naturally in liquid or feed”—is the first to demonstrate the virus can be transmitted easily through the natural consumption of contaminated feed and liquid.
Specifically, it identified ways in which agricultural processing methods for feed ingredients can spread the virus, including drying crops on roadways, a common practice in China. The roads may be contaminated by traffic from trucks containing infected pigs. Further, processing ingredients on contaminated equipment is another possible source of transmitting virus particles to feed.
“Although feed and feed ingredients are a less recognized transmission route for African swine fever, the global distribution of feed ingredients makes this pathway important to consider for transboundary introduction of the virus,” said Megan Niederwerder, DVM, PhD, BSc, assistant professor of diagnostic medicine and pathobiology at KSU.
“Millions of kilograms of feed ingredients are imported from countries where African swine fever virus is currently circulating. Our previous work demonstrated that a wide range of feed ingredients promote survival of the virus after exposure to environmental conditions simulating transboundary shipment.”
The team’s next step is to identify ways to reduce or eliminate this risk, such as chemical additives, storage time, or heat treatments.
“African swine fever is arguably the most significant threat to worldwide swine production,” said Dr. Niederwerder, who led the research team.
“With no effective vaccine or treatment, preventing introduction of the virus is the primary goal of countries free of the disease. Our hope is this research will further define possible routes of disease spread and develop mitigation strategies to prevent introduction into the U.S. swine herd.”
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