Disinfection and conditions associated with thermo-assisted drying and decontamination inconsistently produce negative PRRSV rRT-PCR results on metal surfaces.

Because contaminated livestock trailers are a significant risk for transmitting viruses between herds, various methods of washing, disinfecting, and thermo-assisted drying and decontamination (TADD) have been evaluated for their effectiveness in inactivating porcine reproductive and respiratory syndrome virus (PRRSV) on contaminated surfaces. Information on when to expect negative qRT-PCR results after adequate trailer sanitation is lacking. The objective of this study was to evaluate whether there are conditions associated with washing-disinfectant-TADD procedures that will consistently produce a negative qRT-PCR result for the purpose of monitoring compliance with trailer sanitation and decontamination protocols for PRRSV on metal surfaces. 144 diamond plate aluminum coupons were spiked with PRRSV or phosphate-buffered saline (PBS) and treated with a designated disinfectant protocol. Disinfectants evaluated included multiple accelerated® hydrogen peroxide (AHP) disinfectants and a quaternary ammonium and glutaraldehyde combination disinfectant. Disinfectant was applied for 5 or 60 minutes of contact time at either 20 °C or -10 °C in a matrix of feces or PBS. All coupons were heated until the surface temperature of the coupon reached 71 °C and then held for 10 minutes to simulate TADD under field conditions. Post-treatment swabs for all treatment groups, except negative control groups, were positive by PRRSV qRT-PCR. Under the conditions evaluated in this study, consistently negative qRT-PCR results after treatments were not found. Therefore, for the purpose of monitoring compliance with trailer sanitation and decontamination protocols for PRRSV, alternatives to qRT-PCR should be explored.

Evaluation of a peroxygen-based disinfectant for inactivation of porcine epidemic diarrhea virus at low temperatures on metal surfaces.

Porcine epidemic diarrhea virus (PEDV) spread rapidly across the United States in part due to contaminated livestock trailers. The objective of this study was to test a peroxygen-based disinfectant for the ability to inactivate PEDV on aluminum surfaces at 4 °C or -10 °C. Forty 3-week-old individually housed barrows were used as a bioassay to determine the infectivity of PEDV after treatment with either a 1:100 or 1:600 dilution of a peroxygen-based disinfectant with 10 or 30 min of contact time. One coupon matched to one pig was the experimental unit. Coupons in the positive control and disinfectant treatment groups were contaminated with 2 mL of feces spiked with PEDV. A negative control group was contaminated with PEDV-negative feces. Following treatment, the feces and disinfectant remaining in the coupons was collected and administered to pigs intragastrically. Rectal swabs were collected from pigs 3 and 7 days post-inoculation (DPI) and tested for PEDV by RT-qPCR. Samples from all coupons, except the negative control, were positive by RT-qPCR for PEDV before and after treatment. All rectal swabs from the pigs in the negative control and the seven disinfectant treatment groups were RT-qPCR negative for PEDV on 3 and 7 DPI. All pigs in the positive control at 4 °C and 3 of 4 pigs in the positive control conducted at -10 °C were RT-qPCR positive for PEDV on 3 and 7 DPI. Both the 1:100 and 1:600 dilutions of peroxygen-based disinfectant successfully inactivated PEDV under the conditions of this study.