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Viral pathogens survive shipping demonstration

Colleen Kottke
Wisconsin State Farmer
Researchers expand understanding of virus transmission in feed during 6000 mile journey.

As African Swine Fever decimated China's hog herds on the other side of the world, the US pork industry and the USDA has been on high alert to prevent the devastating disease from entering the country.

Upgrading bio-security and best practices on the farm, restricting imports of pork and pork products from affected countries and safeguarding ports of entry by increasing passenger and baggage screening have proven successful...so far.

But researcher Scott Dee says its only a matter of time before the virus appears in the US.

Working with funding provided by the Swine Health Information Center (SHIC), Dee and his team at Pipestone Applied Research have been studying the risk of virus movement in feed. Early work in the laboratory confirmed the survivability of porcine epic diarrhea virus (PEDV) in feed as the vehicle for transmission and transport.

An eye-opening demonstration project performed by Dee and his team showed just how viable certain viruses can remain in feed products during transport. Results indicated the presence of viable porcine reproductive and respiratory virus (PRRSV), Senecavirus A (SVA), and PEDV in both soy products, while viable SVA was recovered from all five tested feed ingredients. In contrast, survival was limited in the vitamins and amino acid ingredients.  

Using feed samples laced with viruses loaded in containers on a truck, the viral pathogens traveled 6000 miles over the course of 21 days, crossing 14 states. Beginning in Minneapolis, the truck headed south to Iowa and from Colorado to Texas, across the southern coast, up the eastern seaboard, and back to the Midwest. The virus-spiked feed was exposed to mountainous, western, gulf coast, eastern, and New England environments as well as Midwestern.

“We wanted to expose the viruses to as many environments as possible in the continental US,” Dee said. “This was like an actual commercial journey.”

Upon the truck’s return to Minnesota, the feed samples were tested with SVA being found in every feed ingredient evaluated. The result is what Dee had been seen previously in the lab, that SVA – a surrogate of food-and-mouth disease – survives and is stable in feed ingredients.

Dee also pointed out that PEDV and PRRS viruses also survived in feed — confirming that soy-based products are supportive of viruses; both organic and inorganic soybean meal were included with viruses thriving in each, the report showed.

Dee said that great care was taken during the project with samples being well contained in boxes securely loaded in the trailer without risk for spills. No other cargo was in the trailer and the only stops made were for fuel and overnight rest.

“We wanted to protect the sanctity of agriculture,” Dr. Dee said in the release. “These were not foreign animal diseases. We talked to the Board of Animal Health director and USDA. If we were managing the demonstration as described, they were perfectly fine with it.”

The amount of feed in this demonstration was small – just 30 grams per test. This allowed for the entire quantity of feed to be tested at the conclusion of the journey so there were no false negatives. Because this was a proof-of-concept project, a larger scale demonstration is next on Dee’s agenda for this fall.

“We’re going to do this whole thing again in November, using one ton totes of organic and inorganic soybean meal,” he said. “We will get away from the 30 gram amounts and into a representative volume producers are dealing with all the time in tons.”

When these ingredients return, sample testing will be completed. The same route, viruses, and feed products will be used.

“This helps bridge the gap from lab to the real world,” he said, adding that the results should help people gain more confidence with evidence viruses can live in feed under a commercial shipping event.