1. 1Division of Gastroenterology, Children's Hospital and Medical Center and Departments of Pediatrics and Microbiology, University of Washington School of Medicine, Seattle, Washington 98105
2. 2Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington 99164
3. 3Field Disease Investigative Unit, Washington State University, Pullman, Washington 99164
4. 4Acute and Communicable Disease Program, Oregon Health Division, 800 NE Oregon Street, Suite 772, Portland, Oregon, 97232
5. 5Washington State Department of Health, Communicable Disease/Epidemiology Section, Seattle, Washington 98155