1. The Ohio State University - College of Veterinary Medicine, Department of Veterinary Preventive Medicine and College of Public Health, Division of Epidemiology, A188 Sisson Hall, 1920 Coffey Road, Columbus, OH 43210 USA
2. The Ohio State University - College of Veterinary Medicine, Department of Veterinary Preventive Medicine, A180 Sisson Hall, 1920 Coffey Road, Columbus, OH 43210 USA
3. University of Gondar - College of Veterinary Medicine and Animal Sciences, Maraki Street, Gondar, Ethiopia