1. Biomedical and Diagnostic Sciences, College of Veterinary Medicine, The University of Tennessee, Knoxville, TN, USA
2. Section of Veterinary Public Health, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
3. Department of Agriculture and Animal Health, College of Agriculture & Environmental Sciences, University of South Africa, Johannesburg, South Africa