1. Southeastern Cooperative Wildlife Disease Study, College of Veterinary Medicine, The University of Georgia, Athens, Georgia 30602, USA
2. Current address, National Biological Service, National Wildlife Health Center, 6006 Schroeder Road, Madison, Wisconsin 53711, USA
3. U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, National Veterinary Services Laboratories, 1800 Dayton Road, Ames, Iowa 50010, USA