A closer look at PEDv's journey from China

When Porcine Epidemic Diarrhea virus (PEDv) hit North America in 2013, it had many in the swine industry scratching their heads wondering how and why?

For any of you that were listening during your high school history classes, history tends to repeat itself.

Dr. Scott Dee with Pipestone Applied Research knew that in order to prevent an infectious disease like PEDv having such a devastating impact in the future, we had to learn from our history to improve.

In 2015, Pipestone released research on PEDv in Feed Ingredients, finding that certain ingredients support live virus (including SBM, meat and bone meal, red blood cells, and DDG's) while others did not.

Pipestone proved that PEDv can survive in certain feed ingredients and infect pigs.

That left another question to be answered:

Could PEDv have survived the trip from China and remained infectious?

Why China?

When we look at the strain of PEDv that came into our country in 2013, it matched very closely (99.5%) to a strain of the virus that came from a specific province of China. The United States also regularly imported a lot of material from China that are pertinent for pork production.

Using a laboratory model and a website called SeaRates.com, PAR simulated a 37-day journey, crossing the Pacific Ocean from China to San Francisco, port stops for clearing customs, and the 1800 mile trip by truck across Interstate 80 to Des Moines, Iowa - the heartland of pork production.

To simulate the environmental conditions that cargo would encounter during this trip, Pipestone used an instrument called an environmental chamber that can reproduce temperature and humidity fluctuations on a daily basis.

They then imputed historic weather data that reflected the period of December 2012 to January 2013, before clinical signs were first reported (April 2013).

Small, plastic baby food containers held standard quantities of different ingredients which were contaminated with equal levels of PEDv.

The samples were tested 4 times throughout the model, including the time when the ingredients entered the US and were shipped to Des Moines.

Below are the results.

The first column lists the ingredients used in the study, while the 2nd

column indicates the presence of virus (dead or alive).

To determine whether PEDV survived the journey and was alive at the end of the 37-day period, VI (Viral Isolation) and Bioassay were employed.

VI tests for live virus in cell culture in the laboratory, where bioassay involves the inoculation of the samples into naïve baby piglets.

The first five ingredients in the list (Soybean meal (SBM) conventional, SBM organic, Lysine, Vitamin D, and Choline) all demonstrated the presence of live virus at the end of the journey.

While the other ingredients had viral RNA by PCR ,

the virus was no longer alive.

Pipestone Applied Research also had a sample of each ingredient that was treated with a product called Sal-Curb, and a sample of each ingredient that was treated with MCFA (Medium Chain Fatty Acid blend).

All ingredients treated with either product were negative for live PEDv by both VI and bioassay.

"We need more work in this area," says Dr. Scott Dee, "But it is promising that we may have ways to protect our industry by treating and neutralizing virus in feed."

Back to the main question, "Could PEDv have survived the trip from China and remained infectious?"

The answer: "Under the conditions of the study: Yes."

While it's only an experiment, these are the first objective data that support the idea that contaminated feed ingredients may be a risk factor for PEDV entry to the US. In addition, it is one step further in understanding the history of disease transmission at a global level, and continues to re-inforce the importance of not letting history repeat itself!

Pipestone Applied Research will continue to have a focus on PEDv transmission and how we can prevent future outbreaks of other transboundary foreign animal diseases, such as Foot and Mouth Disease and Hog Cholera.

For questions on this research trial, contact Dr. Scott Dee at 507.825.4211 or at sdee@pipevet.com.

 
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