1. Department of Infectious Diseases, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611, USA
2. Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Rorida, Gainesville, Florida 32610, USA
3. Current address: 18520 County Road 6 North, Plymouth, Minnesota 55447, USA
4. United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, P.O. Box 70, Ames, Iowa 50010, USA
5. Current address: Room 2132 Veterinary Medical Building, Iowa State University, Ames, Iowa 50011, USA
6. Current address: P.O. Box 1542, Melrose, Florida 32666, USA
7. Current address: Rollins Animal Disease Diagnostic Laboratory, P.O. Box 12223, Raleigh, North Carolina 27605, USA
8. Florida Game and Fresh Water Fish Commission, Wildlife Research Laboratory, Gainesville, Rorida 32601, USA
9. Current address: 1600 North East 23rd Avenue, Gainesville, Florida 32609, USA