1. Department of Veterinary Public Health and Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, Thailand.
2. Department of Veterinary Medicine, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, Thailand.
3. Rickettsial Diseases Research Program, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, Maryland, USA.
4. Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.
5. International Visiting Scholar, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, Thailand.