The porcine epidemic diarrhea virus (PEDV) has killed at least 4 million young pigs since being identified in the U.S. one year ago. A research team led by University of Illinois veterinarian James Lowe recently concluded and published a study investigating how the devastating virus is being spread. Lowe is a clinical instructor in the department of veterinary clinical medicine, where he teaches production medicine. He also conducts a private practice, and assists livestock producers with strategic decision-making and process improvement through his firm Lowe Consulting Ltd. Lowe spoke recently with News Bureau writer Sharita Forrest about the research team’s findings.
What was the nature of the study that your research group conducted and what did you find?
We did some work last summer to investigate the role that livestock transportation – the trucks that take pigs to market – has played in the spread of the disease early in the outbreak. We had a great collaboration of practicing veterinarians in six Midwest states who went out to packing plants and sampled 100 trucks at each plant before and after they unloaded. We wanted to determine if the trucks were contaminated with PEDV before they arrived or were they contaminated at the plants.
The data indicate that for every truck that entered the plants contaminated, two trucks were contaminated when they exited. That was consistent across all the plants.
There are people who walk on and off between the trucks and the loading docks, such as truck drivers and people who work in the plants. We had some evidence to suggest that the more contact between the people in the plant, the inside of the trailer and the truck driver, the more likely the trucks were to be contaminated at departure. We surmised that they were carrying the virus on their boots.
Are decontamination measures in place to prevent the spread of diseases in this manner?
Currently, we wash, chemically disinfect and then dry those trailers – and drying is the critical step. There are a couple of ways to dry them. We allow them to sit, or, commonly, we heat the trailers by putting them in a room with a giant furnace and blowing hot air into them so they heat up to 160 degrees F.
But, really, the “trailer baker” method isn’t any more effective than allowing the trailers to dry on their own. It’s just that in cold weather, it’s hard to get a spot inside, and the trailers tend to freeze instead of dry when sitting outdoors.
In the U.S. today, we currently don’t have enough trailers and enough truck washes to wash all the trailers that transport livestock. It takes about two hours to wash a truck, and another hour for it to dry. If every time we hauled a load of pigs we had to dry the trailer in between, the trucks couldn’t get as many pigs hauled in a day; therefore, we would need many more trailers.
It takes a lot of money to buy trailers, build truck washes and hire enough drivers. Until now, it did not appear that the returns – the reduction in potential disease spread – on washing and drying trailers were high enough to justify the investment for all of the pigs that were moved to market.
It costs about $1.50 per pig – or about 1 percent of the total production cost – to wash and dry a trailer. So producers tend to not get much of a financial return in washing and drying every trailer that’s used to move pigs to market.
However, it is common practice to wash and dry all the trailers that haul pigs between farms. As an example, all the trailers that move baby pigs between farms – or those that move replacement-breeding stock – are routinely washed and dried.
We knew that we had a system that was at high risk, but in the study we wanted to see how high of a risk that is. Our data suggested that it’s a real issue.
How can the system be fixed and the disease outbreaks controlled?
The way around it long term will be building more truck washes, buying more trailers and changing some internal procedures so that the sites with baby pigs don’t ever have contact with the market facilities.
We need to start thinking about how to separate the systems that breed pigs from the facilities that raise them. We share a lot of people and things among the facilities for both herds – trucks, trailers and drivers; maintenance personnel; and people who deliver supplies.
The devastation with this disease is in the breeding herd. The virus affects all pigs, but in older pigs it’s pretty mild. In pigs under 7 days’ old, PEDV is basically 100 percent fatal. There’s nothing we can do to save those piglets.
We’ve made a lot of progress in the past year, but there’s still a lot that we don’t know.
Are researchers any closer to knowing the origins of the virus and its path into the U.S.?
We know that the first case was diagnosed in Ohio, and that the genetic origins of the virus are Chinese. But we don’t know how it got from Asia to the U.S. or exactly when it was introduced. It could have been here for months before we actually got lucky and found it.
PEDV could have gone undetected in finishing barns for months before the Ohio case was diagnosed because it looks very similar at first to another disease, transmissible gastroenteritis (TGE). TGE is very common in finishing barns, and because it’s very mild and not fatal, we tend not to test for it, and rely on clinical signs to make diagnoses.
Was the U.S. just caught unprepared for the PEDV outbreak?
PEDV is not a disease that’s regulated by the federal government or part of the bucket of diseases that the U.S. Department of Agriculture’s veterinary service deals with. So they did not have a formal response plan when the disease showed up, and didn’t move very quickly at the beginning.
There are a lot of conversations going on about how do we tighten that up, which will be critical to preventing the next disease outbreak. With the amount of global trade, we are going to continue to have diseases that enter the U.S. from other countries. We’ve got to figure out how to build a system that protects the U.S. livestock system against that in the long term.
We have always relied on the USDA to help us prepare for these things, and as a society, we’ve let USDA become grossly underfunded. They don’t have the resources that they’ve always had. And we’ve also significantly cut funding for agriculture and animal infectious disease research, gutting our research capacity at this and other universities across the country.
In recent weeks, the USDA announced that it would require tracking of pigs, vehicles and other equipment leaving infected facilities. How are producers going to be affected by that?
We don’t know yet how it’s going to affect us because the announcement did not provide any detail and didn’t indicate that any direct funding was available to support it. The American Association of Swine Veterinarians, the National Pork Board and the National Pork Producers Council will be working closely with the USDA to shape that program.
We believe that the important part of that program will be building the infrastructure to deal with the next disease. USDA has not said at this point that they are going to restrict movement of livestock with PEDV. What they really want to do is build a data-capture system to help us understand where the virus is and how it’s moving. We are supportive of those efforts if done correctly because we think they’ve worked for a lot of other diseases.
PEDV isn’t transmissible to humans or other species. But what is its impact likely to be on producers and consumers?
PEDV is clearly going to reduce the pork supply, and consumers will feel it at the grocery store.
Swine producers whose pigs contract this disease are going to lose at least 10 percent of their production and revenue for the year – without reduction in costs. Profits are going to decline drastically in the industry.
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