Power washing, disinfection and heated drying are proven ways to clean transport trailers. But these methods are labor intensive and not readily mobilized in the event of a disease outbreak, says Lisa Becton, DVM and associate director of the Swine Health Information Center (SHIC).
“Effective biosecurity protocols for swine transport are critical to controlling endemic pathogens like porcine epidemic diarrhea virus (PEDV) and preparing for foreign animal diseases such as African swine fever,” Becton says.
The investigation of alternative or novel methods to achieve transportation sanitation and reduce the spread of pathogens was one of the key priorities for the SHIC Wean-to-Harvest Biosecurity Research Program.
“If alternative methods could be identified that can minimize swine pathogens in trailers, producers could have the ability to select a sanitation method that is best fit within their farm operation,” Becton points out.
Promising Alternatives
A recent study led by Erin Kettelkamp, DVM, with the Swine Vet Center, evaluated the combination of two methods of decontamination, including removal of gross organic materials by an industrial vacuum and the application of hydrogen peroxide-based aerosol disinfectants to reduce virus levels in contaminated trailers and prevent disease transmission.
The study of modified vaporous hydrogen peroxide (mVHP), which has been used successfully in military and biosafety level 4 laboratory settings due to its effectiveness in neutralizing biological agents across diverse materials without equipment degradation, shows promise. Hydrogen peroxide-based aerosol disinfectants have been shown to inactivate swine pathogens in previous work done by Dr. Kettelkamp.
Unlike current wash and thermo-assisted drying and decontamination procedures, this equipment used for this combined approach is portable, waterless and scalable, significantly reduces labor, infrastructure and water usage associated with existing practices. In addition, this technology may be valuable during disease outbreaks, when the rapid and thorough biocontainment of contaminated swine transport vehicles is critical.
A Look at Two Scenarios
For this pilot study, two scenarios were evaluated: 1) mock-swine trailer under in-vitro conditions (i.e., chamber) and 2) mock-swine trailer under field-simulated conditions (i.e., shroud). For the second scenario, a miniature insulated trailer shroud was designed to mimic conditions for potential field application. A miniature aluminum trailer model was contaminated with PEDV fecal inoculum in both scenarios. An industrial-grade vacuum was used to remove organic material, followed by applying mVHP treatment across different contact times.
PEDV inoculum was mixed with feces and shavings to prepare the contamination material. Aluminum trailer models (1:16 scale) were contaminated with PEDV fecal inoculum and treated with mVHP for 30, 60, or 120 minutes. Four replicates per treatment duration were performed, with positive controls held at ambient temperature.
Pre-marked trailer surfaces were sampled before and after treatment to confirm PEDV contamination and to assess differences in PEDV RNA detection via quantitative PCR. Bioassays were conducted via oral inoculation with post-treatment environmental samples, utilizing liquid that was recovered from the trailer after treatment. Pigs were observed for clinical signs and evidence of PEDV infection to determine if the virus had been inactivated with each treatment. Researchers assessed the main effects of disinfectant treatment and contact time, as well as their interaction.
Takeaways for Producers
In this pilot study, mVHP treatment of contaminated trailers showed a reduction of detectable PEDV genetic material via PCR from contaminated trailer surfaces compared to untreated controls. No differences in PEDV detection levels via PCR Ct values were observed across different contact times. The impact of mVHP treatment on PEDV infectivity was inconclusive; therefore, additional research is needed to validate virus inactivation capabilities and to improve the standardization of contamination methods to optimize bioassay procedures and to ensure its application and scalability in the field. With continued development, this approach could play an important role in improving transport biosecurity and disease outbreak response readiness for the swine industry.
“Transport biosecurity is a challenging problem, and continued investigation is critical to identify effective novel or alternative methods for trailer sanitation,” Becton says.
This study was funded by the Swine Health Information Center Wean-to-Harvest Biosecurity Research Program, in partnership with the Foundation for Food & Agriculture Research and Pork Checkoff.
