1. Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5601, USA
2. Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5601, USA
3. USGS, Patuxent Wildlife Research Center, 11510 American Holly Drive, Laurel, Maryland 20708-4019, USA