A Porcine Epidemic Diarrhea Virus Outbreak in One Geographic Region of the United States: Descriptive Epidemiology and Investigation of the Possibility of Airborne Virus Spread

Beam, Andrea; Goede, Dane; Fox, Andrew; McCool, Mary Jane; Wall, Goldlin; Haley, Charles; Morrison, Robert

Direction of PEDv disease spread was analyzed and qualitatively compared with the wind data. Two methods were used to describe the direction of disease spread during the outbreak: the linear directional-mean function in ArcGIS and the direction method in ClusterSeer. All PEDv cases (including positive-placed sites) were included in the analysis to determine the direction of pathogen spread. For the first method, general direction was determined by first calculating the mean geographic center of incident cases for each day of the outbreak. The mean geographic centers were then used to create a vector indicating the direction and distance of PEDv spread from one day to the next for each day of the outbreak. These mean daily vectors were then used as inputs to the linear directional-mean function in ArcGIS. The linear directional-mean function outputs a single vector indicating the mean direction and mean distance of PEDv spread for all cases (Fig 1) . The function also outputs numeric values indicating the average distance of pathogen spread, average direction of spread, and a directional variance value indicating how much the daily vectors deviate from the average direction.