1. Department of Veterinary Pathology, Armed Forces Institute of Pathology, Washington, D.C. 20306, USA
2. Zoonotic Diseases Laboratory, Livestock and Poultry Sciences Institute, Agricultural Research Service, U.S. Department of Agriculture, BARC-E, Beltsville, Maryland 20705, USA
3. Animal Hospital of St. Petersburg, St. Petersburg, Florida 33702, USA