To better understand how swine viruses spread during transport, the Swine Health Information Center funded a Wean-to-Harvest Biosecurity Research Program study focused on the unloading process at the harvest plant, in partnership with the Foundation for Food & Agriculture Research and Pork Checkoff. Led by Drs. Cesar Corzo and Lucas Ferreira at the University of Minnesota, the study tracked the presence of four major pathogens affecting the swine industry as a method to assess trailer contamination dynamics during unloading. Additional objectives were to identify key factors such as season, cleaning practices, and driver behaviors that influence contamination risk. Proper washing, disinfection, and drying of trailers significantly reduce viral contamination risk, while seasonal conditions strongly influence virus presence, requiring adjusted biosecurity strategies year-round.
Read the industry summary of study #24-077 here.
Harvest facilities are recognized as important nodes in the swine industry that contribute to disease transmission networks, yet quantitative data describing environmental contamination dynamics remain limited. The primary objectives of the study were to determine whether trailer contamination increases during pig unloading at the harvest plant and to identify factors such as seasonality, trailer sanitation practices, and driver behaviors that contribute to contamination risk. The study evaluated the occurrence of four swine viruses: porcine reproductive and respiratory syndrome virus (PRRSV), porcine deltacoronavirus (PDCoV), porcine epidemic diarrhea virus (PEDV), and Senecavirus A (SVA) in a commercial harvest plant located in the Midwest. Depending on the virus, between half and over seventy percent of dock samples tested positive. This indicates that the unloading area is a major hotspot for pathogen presence. A substantial proportion of trailers were already contaminated when they arrived at the plant; however, contamination levels increased further after unloading for all viruses evaluated. This demonstrates that trailers not only bring pathogens into the facility but can also acquire additional contamination during the unloading process.
To perform the study, sampling was conducted every two weeks over a one-year period at the commercial harvest facility. Prior to pig unloading, drivers were approached and asked to participate in a short biosecurity trailer survey. If drivers agreed, surveys were completed immediately and data was collected on trailer cleanliness, trailer origin and destination, driver biosecurity practices during unloading, and whether plant employees enter the trailer during the unloading process. Environmental samples were then collected from 1) the unloading dock, 2) the trailer upon arrival before unloading pigs, and 3) the same trailer after unloading prior to departure. Trailer samples were collected by rubbing a sterile cloth moistened with media across a 1ft x 1ft floor area of the compartment in front of the trailer back door.
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