1. Department of Pathobiological Sciences School of Veterinary Medicine Louisiana State University Baton Rouge Louisiana 70803 USA
2. Louisiana Animal Disease Diagnostic Laboratory Louisiana State University Baton Rouge Louisiana 70803 USA
3. Louisiana Department of Wildlife and Fisheries District 2 Monroe Louisiana 71203 USA
4. Department of Microbiology, Immunology, and Tropical Medicine George Washington University Washington D.C. 20052 USA
5. Department of Biosciences University of Oslo Oslo 0586 Norway
6. Aquatic Animal Health Laboratory Department of Medicine and Epidemiology School of Veterinary Medicine University of California Davis California 95616 USA
7. Department of Pathobiology and Population Medicine College of Veterinary Medicine Mississippi State University Stoneville Mississippi 39762 USA