Descriptive and risk analysis of vehicle movements linked to porcine reproductive and respiratory syndrome and porcine epidemic diarrhea transmission in U.S. commercial swine farms.

Vehicle movements, including cabs and trailers, play a role in the spread of swine diseases. However, significant information gaps remain regarding vehicle movement patterns and their role in disease transmission, which, if uncovered, could improve preventive strategies. In this study, we described the movement patterns of vehicle cabs and trailers and identified vehicle-mediated factors associated with porcine reproductive and respiratory syndrome (PRRS) and porcine epidemic diarrhea (PED) farms. We collected global positioning system (GPS) movement data from vehicle cabs and trailers for 18 months, along with infection information for 6621 commercial swine farms in the U.S. For the vehicle movement data, we calculated 66 variables and evaluated their association with sow farms' PRRS and PED status. Our univariate analysis identified 56 variables that were significantly associated with PRRS and PED farm status (p<0.05). Within these variables, vehicle visit frequency and previous exposure to positive farms were the main risk factors for both diseases. Whilst increased vehicle cab and trailer loyalty for farm shipments and vehicle cleaning and disinfection events were protective factors. In the multivariate model, each additional weekly visit by a vehicle cab that had been exposed to a positive farm one day before shipments was associated with an odds ratio percentage change (ORPC) of 305% for PRRS and 286% for PED positivity. Previous exposure to positive farms remained associated with disease status when vehicle cabs were analyzed separately by pig-transport role, with non-pig-transport vehicles showing the strongest association for PRRS (ORPC = 1562%) and pig-transport vehicles for PED (ORPC = 1501%). Our analysis revealed that vehicle contact history played a crucial role in the transmission of PRRS and PED, with relevant associations observed for both pig-transport and non-pig-transport vehicles. These findings contribute to the development of targeted biosecurity, vehicle management, and surveillance strategies to reduce transmission and outbreaks linked to vehicle movements in swine production.