Evaluation of methods for inactivating porcine epidemic diarrhea virus (PEDV) in livestock trailers
Since the introduction and detection of PEDV in the US in the spring of 2013, the swine industry has witnessed incredibly rapid spread of the virus to sow herds and growing pigs across the geographical US. The swine industry is an "industry on wheels," with transport of large numbers of swine across the country every day. It is not surprising then, to discover that contaminated livestock trailers have played a role in the movement of this virus. We cannot quickly change the mobile nature of swine production, but we can identify and implement effective decontamination procedures for contaminated livestock trailers.
The body of literature reviewing inactivation of PEDV is very small, but there are a great number of studies that describe inactivation of other, structurally similar, coronaviruses. These studies indicate that several of the typical methods employed for livestock trailer decontamination, e.g. chemical disinfection and exposure to high temperatures, as well as other environmental conditions such as alkaline pH and high relative humidity, or prolonged time at moderate temperatures were all capable of effectively inactivating coronaviruses. Additionally, it was evident that the presence of proteins around the virus (as might be present in feces) decreased the effectiveness of both heat and disinfectant at virus inactivation, and that chemical disinfectants are more effective when applied at higher temperatures.
To directly investigate the ability of high temperatures to inactivate PEDV in the context of a livestock trailer and TADD facility, original research was conducted to evaluate multiple temperatures applied to PEDV-contaminated feces on aluminum trays. PEDV inactivation was determined via swine bioassay. In this study only 71°C for 10 minutes and 20°C for 7 days were capable of preventing PEDV-infection in 100% (4/4, each) of the swine bioassays.
A second study evaluated the ability to eliminate and inactivate PEDV through the use of high pressure washing with detergent, application of a combination gluteraldehyde and quaternary ammonium chloride disinfectant, Synergize, with and without heating at various temperatures. Swine bioassay again was used to determine infectivity. In this study, all treatments groups resulted in inactivation of PEDV to a level of preventing infection of 100% (4/4) of swine bioassays.
The combination of these studies and review suggest that a sound trailer decontamination program should focus on removal of fecal and organic material, followed by chemical disinfection, and finally heating to high temperature. Each of these steps when performed in combination will be more effective than each by itself, i.e. "the whole is greater than the sum of its parts." These suggestions represent procedures that can be easily implemented in today's swine industry. Although trailers and decontamination facilities are in short supply, the knowledge and technology to accomplish these processes is widespread and should be more widely adopted to prevent the continued spread of PEDV.