1. Saint Louis Zoo Institute for Conservation Medicine, 1 Government Dr., St. Louis, Missouri 63110, USA
2. Saint Louis Zoo Department of Animal Health, 1 Government Dr., St. Louis, Missouri 63110, USA
3. Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2187 Mowry Rd., Bldg. 0471, Gainesville, Florida 32611, USA
4. Wildlife Epidemiology Laboratory, University of Illinois College of Veterinary Medicine, 2001 S. Lincoln Ave., Urbana, Illinois 61802, USA