1. Centers for Disease Control and Prevention, National Center for Infectious Diseases, Hematologic Diseases Branch, Atlanta, Georgia
2. The Rollins School of Public Health of Emory University, Department of Epidemiology, Atlanta, Georgia
3. Centers for Disease Control and Prevention, National Center for Infectious Diseases, Hematologic Diseases Branch, Atlanta, Georgia and The Rollins School of Public Health of Emory University, Department of Epidemiology, Atlanta, Georgia
4. Centers for Disease Control and Prevention, National Center for Infectious Diseases, Hematologic Diseases Branch, Atlanta, Georgia and The Rollins School of Public Health of Emory University, Department of Epidemiology, Atlanta, Georgia