A study led by Dr. Gustavo Machado of North Carolina State University, aimed to reduce the risk of disease transmission between farms through vehicle contacts. The study evaluated reduction of risk through rerouting vehicles while considering cleaning and disinfection events and effectiveness. Findings demonstrate that a vehicle rerouting system holds potential as a strategic tool for preventing and controlling the spread of diseases among farms through vehicle movements.
The study was funded by the Swine Health Information Center Wean-to-Harvest Biosecurity Research Program, in partnership with the Foundation for Food & Agriculture Research and Pork Checkoff. Find the study industry summary here.
Substantial evidence indicates that vehicle movement is closely linked to the spread of diseases among animal production sites. To mitigate disease transmission events, vehicles undergo thorough cleaning and disinfection (C&D) procedures. However, C&D effectiveness remains a question and the frequency of C&D between farm visits is often unknown. Consequently, relying solely on vehicle C&D may be insufficient to stop the spread of diseases, and supplementary strategies are needed to prevent disease transmission events through contaminated vehicles. The objective of this study was to reduce the risk of between-farm transmission through vehicle contacts by rerouting vehicles while considering C&D events and effectiveness.
To conduct this study, data from commercial swine farms were utilized, including farm geolocations, vehicle Global Positioning System data, PRRSV infection status, and PEDV infection status. Among the data collected were the movements of 654 vehicles in a pig-dense area of the US, including vehicles visiting farms, C&D, slaughterhouses, feed mills, and parking locations. Farm data was collected from enhanced on-farm Secure Pork Supply biosecurity plans available in the Rapid Access Biosecurity application (RABappTM). The investigative team (Drs. Galvis and Machado) ranked and reorganized vehicles delivering animals and feed to farms according to several conditions, including disease status of visited farms, vehicle contact network communities, C&D events, and shipment time efficiency.
Using these conditions, researchers simulated vehicle movements for one week, indicating each vehicle was cleaned and disinfected after each shipment. They reconstructed the between-farm contact network by vehicle movements from observed and simulated data and compared 1) the number of contacts from PRRSV-positive and PEDV-positive farms to disease-free farms and 2) the number of contacts between farms from different network communities (group of farms densely interconnected). In addition, researchers calculated the frequency of vehicles visiting C&D stations and traveled distances.
Implementing the rerouting system led to a substantial decrease in the median number of at-risk contacts between farms. For vehicles transporting feed, at-risk contacts were reduced by 42% when C&D effectiveness was 0% and reduced by 89% when C&D effectiveness was 50%. For vehicles transporting pigs to market, at-risk contacts were reduced by 25% when C&D effectiveness was 0% and reduced by 45% when C&D effectiveness was 50%. Vehicles transporting pigs between farms only showed a remarkable reduction after C&D effectiveness was above 50%, with 33% fewer at-risk contacts. Finally, when C&D effectiveness was increased to 100%, at-risk contacts dropped below 5% for vehicles transporting feed and pigs to market, and below 37% for vehicles transporting pigs to farms.
The researchers’ rerouting system also reduced the interactions between farms from distinct network communities. At-risk contacts were reduced by 17% when C&D effectiveness was 0% and reduced by 99.9% with C&D effectiveness at 100%. Furthermore, the rerouting system increased C&D visits by up to 81% and increased the distance traveled per vehicle up to 54%.
Despite the potential benefit of reducing the risk of disease spread between farms, the rerouting system would increase transport costs due to increased C&D events and the distance traveled per vehicle. Given the severe economic impact of PRRSV, PEDV, and other endemic infectious diseases on swine production, the costs and logistics of a vehicle rerouting system will require a close economic examination to justify the potential health benefits of reducing disease transmission compared to continuing traditional vehicle movement schedules and C&D protocols.
This study demonstrates that combining vehicle rerouting movements with stringent C&D practices effectively reduces contact between disease-positive and disease-negative farms. Further, rerouting reduces at-risk contacts between farms from different network communities, thereby reducing the probability of disease dissemination. Ultimately, the rerouting system could be integrated into regular vehicle shipment schedule operations as an additional tool for preventing and controlling the spread of livestock diseases among farms via the indirect contact network of vehicle movements.
Foundation for Food & Agriculture Research
The Foundation for Food & Agriculture Research (FFAR) builds public-private partnerships to fund bold research addressing big food and agriculture challenges. FFAR was established in the 2014 Farm Bill to increase public agriculture research investments, fill knowledge gaps and complement US Department of Agriculture’s research agenda. FFAR’s model matches federal funding from Congress with private funding, delivering a powerful return on taxpayer investment. Through collaboration and partnerships, FFAR advances actionable science benefiting farmers, consumers and the environment. Connect: @FoundationFAR
Swine Health Information Center
The Swine Health Information Center, launched in 2015 with Pork Checkoff funding, protects and enhances the health of the US swine herd by minimizing the impact of emerging disease threats through preparedness, coordinated communications, global disease monitoring, analysis of swine health data, and targeted research investments. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. For more information, visit http://www.swinehealth.org or contact Dr. Megan Niederwerder at mniederwerder@swinehealth.org or Dr. Lisa Becton at lbecton@swinehealth.org.