Scientific Abstract
This experiment aimed to evaluate commercially available disinfectants and their application methods against porcine epidemic diarrhea virus (PEDV) and porcine reproductive and respiratory syndrome virus (PRRSV) on truck cab surfaces. Plastic, fabric, and rubber surfaces inoculated with PEDV or PRRSV were placed in a full-scale truck cab and treated with randomly assigned disinfectants. Treatments were: 1) no disinfectant; 1:256 dilution of Synergize (Neogen Corp, Lexington, KY) applied through 2) misting fumigation (Hurricane Ultra II Portable Elec-tric Fogger, Curtis Dyna-Fog Ltd., Westfield, IN) or 3) pump sprayer (Chapin Sure Spray 1 Gallon Tank Sprayer, Menards, Eau Claire, WI); 1:64 dilution of Intervention (Virox, Oakville, ON) applied through 4) misting fumigation or 5) pump sprayer; 6) 10% bleach (7.55% sodium hypochlorite germicidal bleach; Clorox, Oakland, CA) solution applied through pump sprayer; 7) no chemical treatment for 10 hr; or 8) gaseous fumigation over 10 hr with chlorine dioxide (ProKure G; ProKure Solutions, Phoenix, AZ). After application, surfaces were environmentally sampled with cotton gauze and submitted for PEDV and PRRSV qPCR duplex analysis. There was a disinfectant × surface interaction (P < 0.0001), indicating a detectable amount of PEDV or PRRSV RNA was impacted by disinfectant treatment and surface material. For rubber surfaces, 10% bleach application had lower detectable amounts of RNA compared to all other treatments (P < 0.05) except Intervention via misting fumigation, which was intermediate. In both fabric and plastic surfaces, there was no evidence (P > 0.05) of a difference in detectable RNA between disinfectant treatments. For disinfectant treatments, fabric surfaces with no chemical treatment had less detectable viral RNA compared to the corresponding plastic and rubber (P < 0.05); Intervention via pump sprayer applied to fabric surfaces had less detectable viral RNA than plastic (P < 0.05); 10% bleach via pump sprayer applied to fabric and rubber surfaces had less detectable viral RNA than plastic (P < 0.05); 10 hr downtime with no chemical application or gaseous fumigation for 10 hr applied to fabric surfaces had less detectable viral RNA than other surfaces (P < 0.05).
To build upon this work, an additional investigation was performed to evaluate the efficacy of environmental sample processing technique prior to PCR analysis. Minor differences were observed between techniques depending on the level of organic material present on the surface, but results would indicate that with all levels of environmental contamination centrifugation of environmental samples prior to PCR analysis would result in the most consistent results. Sixteen treatments were evaluated via swine bioassay, but all samples failed to produce infectivity. Applying 10% bleach via pump sprayer had the greatest number of negative samples as evaluated using PCR (9/18) compared to other disinfectant treatments (ranging from 0-2 negative samples), indicating it might be the best disinfectant application if wanting to completely eliminate viral RNA from surfaces. In summary, commercially available disinfectants successfully reduced detectable viral RNA on surfaces but did not eliminate viral genetic material, highlighting the importance of bioexclusion of pathogens of interest.
