1. Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, One Shields Ave., University of California, Davis, California 95616, USA
2. Faculty of Veterinary Science, University of Pretoria, Private Bag X4, Onderstepoort 0110, Republic of South Africa
3. Directorate of Animal Health, P.O. Box 12, Skukuza 1350, Republic of South Africa
4. Kruger National Park, Private Bag X402, Skukuza 1350, Republic of South Africa