1. Department of Medicine, Division of Infectious Diseases, University of Washington, Box 358080, 1959 Pacific Street, Seattle, WA 98195 USA.
2. Division of International Medicine & Infectious Diseases, Weill Cornell Medical College New York, NY 10021, USA.
3. Department of Microbiology, University of Washington School of Medicine, Box 358070, Seattle, WA 98195, USA.