The Science Page today is from researchers Taylor B Parker, Kelly A Meiklejohn, Gustavo Machado, Michael Rahe, Bradford Sean Darrow, and Juliana Bonin Ferreira, who take a look at PEDV contamination on trucks before and after cleaning.
Key Points
- Samples were collected from swine industry truck washes before and after truck disinfection and tested for PEDV RNA contamination using an in-house RT-qPCR assay.
- Overall, cleaning and disinfection did not significantly lower the concentration of PEDV RNA on vehicle exteriors.
- Truck cabin interiors had comparable concentrations of PEDV RNA to vehicle exteriors.
Introduction
Porcine epidemic diarrhea virus (PEDV) is one of the most devastating pathogens of global swine health and welfare. It is well known that contaminated fomites and vehicle movements play an important role in farm-to-farm PEDV spread, but the efficacy of cleaning and disinfection (C&D) protocols on the reduction in dissemination risk via vehicles and trailers remains unclear. This study used data collected from the swine industry to determine how frequently vehicles were contaminated with PEDV RNA before and after C&D.
Materials & Methods
Environmental RNA samples were collected at three eastern North Carolina C&D sites from four different vehicle types: crew truck tires and cabins, feed truck tires and cabins, pigs-to-farm truck trailers and cabins (separated by whether they are serving a confirmed PED+ farm or PED- farm), and pigs-to-market trailers and cabins. A total of 2,004 samples were collected from vehicles before and after C&D with two commercial disinfectants, quaternary ammonium and glutaraldehyde and advanced hydrogen peroxide, each at two different concentrations. An in-house RT-qPCR assay was used to detect the presence of PEDV RNA (not infectivity status).
Results & Discussion
A total of 387 unique cabins, trailers, and tires were included in the study, many being sampled more than once. Results suggest that pigs-to-market trucks were the most likely to be contaminated with PEDV RNA, while feed trucks were the least likely (Table 1). When considering all trailer and tire samples and using Cq values as an assessment of cleanliness, neither disinfectant was able to yield significantly cleaner vehicles after disinfection. Moreover, when considering individual truck types, quaternary ammonium and glutaraldehyde was the more effective disinfectant at eliminating detectable PEDV RNA. Results also show that the cabin interiors of all truck types were not significantly cleaner than the exterior trailers/tires (Table 1). Further studies are needed to evaluate the infectivity of these vehicle samples (in progress); however, based on the presented results, vehicle biosecurity measures involving the disinfection of cabin interiors, as well as market truck disinfection as a whole, should be reevaluated to prevent the spread of PEDV as trucks go back to farms after washing and as personnel enter and exit their cabins.
| TRUCK TYPE | DISINFECTION STATUS | ||||||
| Before Disinfection | After Disinfection | ||||||
| Location of sampling | Advanced Hydrogen Peroxide | Quaternary Ammonium/Glutaraldehyde | |||||
| Cabin | Tire | Back-of-Trailer | 1:40 | 1:32 | 1:128 | 1:100 | |
| PED+ | 50.56% (45/89) | NA | 48.86% (43/88) | NA | NA | 25.00% (7/28) | 36.96% (17/46) |
| PED- | 47.25% (43/91) | NA | 41.57% (37/89) | 41.67% (5/12) | 43.75% (7/16) | 23.81% (5/21) | 16.67% (3/18) |
| Feed | 16.32% (31/190) | 7.60% (13/171) | NA | NA | NA | 26.92% (23/78) | 3.19% (3/94) |
| Market | 87.29% (103/118) | NA | 79.17% (95/120) | 100% (26/26) | 97.22% (35/36) | 70.37% (19/27) | 84.84% (28/33) |
| Crew | 67.65% (23/34) | 30.00% (9/30) | NA | NA | NA | NA | NA |
*NA- Data not available as such samples were not collected from that vehicle type
*Values are reported as follows: Percentage of PEDV RNA positive samples (number of positive samples/total number of samples).