1. Respiratory Diseases Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
2. Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia
3. California Emerging Infections Program, Oakland, California
4. University of California at Berkeley School of Public Health, Berkeley, California
5. Atlanta Veterans Affairs Medical Center, Atlanta, Georgia