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

PEDv spread and the predominant wind direction during the outbreak period generally aligned in a southerly direction (Fig 5) . The circular variance from the linear directional-mean analysis was large (0.81), however, indicating that the daily PEDv vectors used as inputs deviated from the directional mean output. This result indicates variability in the directions of the input vectors. Nonetheless, the average direction of PEDv spread with this methodology was south to slightly southwest, and when positive placed sites were excluded from the linear directional mean analysis, PEDv spread direction was still south. Based on the directional test in ClusterSeer, subsequent cases typically occurred in the southeasterly direction (126.6 degrees 1 on average) to previous cases. The test statistic indicated this directional pattern was statistically significant (p = 0.001; we could reject the null hypothesis that disease spread was in a random direction). The variance indicated there was considerable variation in the angle directions from one case to subsequent cases ("concentration" = 0.20).