Porcine epidemic diarrhea virus (PEDV) continues to pose a significant threat to the U.S. swine industry. Livestock trailers used for transporting pigs play a major role in PEDV epidemiology if not adequately cleaned and disinfected, the Swine Health Information Center (SHIC) explained in a recent report.
In a study led by Rodger Main of Iowa State University and funded by the SHIC Wean-to-Harvest Biosecurity Research Program, in partnership with the Foundation for Food & Agriculture Research and Pork Checkoff, researchers evaluated various cleaning protocols to mitigate PEDV spread from a contaminated trailer to the farm through foot traffic between these two areas.
“Effective cleaning and disinfection of livestock trailers are crucial in mitigating PEDV spread. This study simulated foot traffic between farm-site areas and trailers to mimic field conditions and determined the efficacy of various cleaning treatments,” SHIC explained in an article.
A Look at the Process
Five treatment groups were included in the study. Researchers studied a positive control group, where no trailer cleaning occurred post-inoculation with PEDV. They evaluated a scrape and bake (TADD) group, where trailers were scraped and swept to remove fecal matter followed by heat up to 71ºC. The third group studied a volume hose wash and disinfect method, where trailers were flushed out with a high volume hose followed by disinfectant. The fourth was a power wash and disinfect group where trailers were first washed with a hose to remove gross fecal matter, then power washed at 1500 psi, followed by disinfectant. The final group they evaluated was a negative control group, where trailers were inoculated with PEDV-negative feces and received no cleaning.
The different cleaning methods were applied and followed by a simulation of foot traffic to mimic real-world conditions, the report explained.
Trailers were sampled post-cleaning and after foot traffic simulation. PEDV presence was quantified using qPCR to measure viral load on trailer surfaces and farm loading areas. Bioassays were conducted by inoculating naïve pigs with samples recovered from the farm site area after applying the treatments to trailers. Statistical analyses, including ANOVA and Fisher’s Exact test, compared PEDV levels and positive PCR results across treatments.
What Did the Study Reveal?
“Washing treatments, particularly flush-out volume hose and power wash and disinfect, demonstrated significant efficacy in reducing viral load on both the trailer and farm-site surfaces. For farm-site surface contamination, these methods achieved over 99% reduction in viral genomic copies compared to the positive control,” SHIC reports.
Researchers say this marked reduction is crucial in preventing infection of susceptible pigs and highlights the importance of effective washing protocols.
“The power wash and disinfect method emerged as highly effective, significantly reducing PEDV levels on trailer surfaces with most samples showing negative PCR results (three of five),” SHIC reports. “The volume hose wash and disinfect method also demonstrated substantial efficacy in inactivating the virus as tested through swine bioassay, though some residual fecal material was observed.”
The scrape and bake method reduced viral load by more than 98% compared to the positive control, but this method was not effective in terms of virus inactivation as the most pigs tested on bioassay became infected with PEDV (four of five replicates), the report said.
Overall, bioassay results indicated that only the positive control and scrape and bake treatments led to PEDV infection in pigs, while the other treatments successfully prevented viral transmission, SHIC reports.
“Researchers noted water-based washing procedures, especially power wash and disinfect, are highly effective in reducing PEDV contamination on livestock trailers and preventing transmission to pigs. Importantly, both volume hose and power wash treatments were effective in completely producing negative pigs on bioassays, indicating effectiveness in inactivating the remaining virus harvested from the trailer and farm-site surfaces,” SHIC said.
The study underscores the importance of thorough cleaning and disinfection protocols in enhancing biosecurity in swine production systems, SHIC reports.
“Findings also suggest routinely cleaning and disinfecting all market haul trailers leaving terminal points of concentration by either of the water-based trailer cleaning treatments could reduce inter-premises disease transmission associated with market haul transport and elevate preparedness across the U.S. pork industry,” SHIC said.
Your Next Read: 4 Things We Learned In 2024 to Be Better Pig Farmers in 2025
