1. Department of Veterinary Microbiology & Preventive Medicine, 1116 Veterinary Medicine Complex, Iowa State University, Ames, IA 500111, USA and, Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Henry Dunant Road, Bangkok 10330, Thailand.
2. Department of Veterinary Microbiology & Preventive Medicine, 1116 Veterinary Medicine Complex, Iowa State University, Ames, IA 500111, USA.
3. Department of Veterinary & Microbiological Sciences, North Dakota State University, Fargo, ND 581022, USA.