1. School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA (Hutton, Innes, Schifferli, Rankin)
2. The Research Group on Infectious Diseases in Animal Production, Faculty of Veterinary Medicine, University of Montreal St-Hyacinthe, Quebec, Canada (Harel, Garneau)
3. Center for Translational and Clinical Research and Center for Clinical Epidemiology and Biostatistics, School of Medicine, University of Pennsylvania, Philadelphia, PA (Cucchiara)