In a perfect world, all truck and trailers transporting hogs would be washed, disinfected and dried after every load. But since that is not the case, what are the workable alternatives as we face Porcine Epidemic Diarrhoea Virus (PEDV)? Pork Checkoff-funded research at Iowa State University aimed to get some answers.

Derald Holtkamp, DVM, Iowa State University, said: “We were looking for alternatives between the full-blown - washing, disinfecting and drying trailers - and doing nothing. We didn’t have any alternatives in the middle that would work to at least reduce the risk of PEDV exposure, if not eliminate it entirely.”

Having a practical alternative is particularly important for vehicles transporting market hogs and cull sows.

A field study headed by Jim Lowe, DVM, of the University of Illinois, in the early days of the PEDV outbreak found that trucks/trailers hauling pigs to market were a source of cross-contamination. At the time, 17.3 per cent of the trailers tested positive for PEDV at market. The study showed that each PEDV-contaminated trailer arriving at a plant contaminated between 0.20 to 2.30 additional trailers.

“That’s as close to a smoking gun as you can get,” Dr Holtkamp said. “It tells us we are moving this virus all around.”

So, Iowa State researchers looked at options for trucks/trailers that had been scraped and swept of organic matter but not washed. They focused on finding time and temperature combinations that would inactivate the virus.

In the end, they discovered that only two options worked - heating the trailer to 160°F for 10 minutes or leaving it sit at 68°F for seven days. For the high-end temperatures, researchers concentrated on 145°F and 160°F for 10 minutes.

Dr Holtkamp said: “Heating a trailer to 160 is expensive – it takes a lot of propane or gas. It would be good to see if other time and temperature combinations between 145°F and 160°F would work.” However, he added that given the virulence of PEDV, he would not be surprised if 160°F was the minimum temperature.

Housing a truck/trailer at 68°F for seven days is not feasible for many operations but for producers who haul one load of pigs a week, it offers a solution.

“If you’re storing the trailer in an unheated machine shed - get it into a heated building if you can,” Dr Holtkamp advised.

He offered producers these other take-home points:

• Washing, disinfecting and drying trucks/trailers between loads of pigs is still the gold standard. “If you’re doing that today, we’re not suggesting that you stop,” Dr Holtkamp pointed out. “But when you can’t get that done, the times and temperatures designated in our study provide an alternative."
• The first priority is to scrape and sweep the trailer to get out as much organic matter as possible; then apply heat.
• Heating trailers to 145°F was not effective in killing PEDV; heating to 160°F for 10 minutes was effective. “If you have the ability to bake the trailer, we think that’s a good way to reduce your risk of PEDV,” Dr Holtkamp noted.
• For producers who have the ability, allowing a trailer to sit idle for seven days at 68°F also is effective at mitigating PEDV exposure.

Dr Holtkamp added: “Trucks and transport vehicles have to be part of our PEDV biosecurity efforts. We now know that, if a producer faces constraints that keep him from washing and disinfecting trailers, there are alternatives to reduce the risk of transmitting PEDV between groups of pigs.”

April 2014