1. US Geological Survey–National Wildlife Health Center, 6006 Schroeder Road, Madison, Wisconsin 53711, USA
2. US Fish and Wildlife Service, Washington Fish and Wildlife Office, 510 Desmond Drive, Suite 102, Lacey, Washington 98503, USA
3. US Department of Agriculture, Agricultural Research Service, Animal Parasitic Disease Laboratory, Building 1001, Beltsville, Maryland 20705, USA