In May of 2013, porcine epidemic diarrhea virus (PEDV) was detected in swine for the first time in the United States and spread quickly across much of the country, partly due to the movement of contaminated livestock trailers. The objective of this study was to evaluate two concentrations of an accelerated hydrogen peroxide® (AHP) disinfectant in a 10% propylene glycol (PG) solution to determine if the mixture was sufficient to inactivate PEDV in the presence of swine feces on metal surfaces at -10ºC. Conditions were chosen to mimic those found in commercial livestock trailers in winter-like conditions when a traditional wash is unavailable.
The AHP disinfectant was mixed in a 10% PG solution to prevent it from freezing at -10⁰C. PEDV positive feces (PEDV negative feces for the negative control group) were spread evenly across the bottom of a 6 inch by 6 inch aluminum coupon with 1 inch sides designed to replicate the floor of a commercial livestock trailer. Eight treatment groups representing two AHP disinfectant concentrations (1:16 and 1:32) in a 10% PG solution, two contact times in a -10⁰C freezer (40 minutes and 60 minutes), and two concentrations of feces (5mL and 10mL) in addition to a negative and positive control group were evaluated on the coupons. Following treatment, the contents of the coupons were recollected and administered to 3 week old pigs via gastric tube. These pigs served as a bioassay to determine the infectivity of virus following treatment. Infectivity was determined by detection of virus with reverse transcriptase polymerase chain reaction (RT-PCR) on fecal swabs collected from the inoculated pigs on days 3 and 7 post-inoculation. Each treatment was performed in 4 replicates (4 coupons and 4 pigs per treatment). Pigs in each treatment group were housed separately in raised tubs within the same room.
Bioassay results were PEDV negative in 100% of the pigs in the negative control group as well as all eight treatment groups. Bioassays were PEDV positive in 100% of the pigs in the positive control group.
Additionally, bioassay outcomes for the negative control (Neg) and all of the AHP disinfectant treatment groups were significantly different (p-value < 0.05) than the bioassay outcomes for the positive control group via Fishers Exact Test.
All AHP disinfectant treatment groups were 100% effective at inactivating PEDV in swine feces under winter-like conditions. Both concentrations (1:16 and 1:32) of AHP disinfectant in a 10% PG solution and both contact times tested (40 minutes and 60 minutes) inactivated PEDV in the presence of light and heavy fecal contamination. These results suggest that when washing, disinfecting, and drying the trailer are not possible; using a 1:16 or 1:32 concentration of AHP disinfectant in a 10% PG solution with 40 minutes of contact time is an effective alternative to reduce the risk of PEDV transmission between groups.
Contact information for correspondence:
Dr. Derald Holtkamp DVM, MS
Associate Professor, Iowa State University College of Veterinary Medicine
Business: (515) 294-9611
Mobile: (515) 520-1040
2233 Lloyd Veterinary Medical Center
Ames, IA 50011-1250