1. U.S. Fish and Wildlife Service, La Crosse Fish Health Center–Midwest Fisheries Center, Onalaska, WI 54650 USA
2. U.S. Fish and Wildlife Service, Southwestern Virginia Field Office, Abingdon, VA 24210 USA
3. Department of Pathobiological Sciences and Freshwater & Marine Sciences Program, University of Wisconsin–Madison, Madison, WI 53706 USA
4. U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WI 54603 USA
5. U.S. Geological Survey, National Wildlife Health Center, Madison, WI 53711 USA