1. Arnold School of Public Health, University of South Carolina, Columbia, South Carolina.
2. Department of Health and Environmental Control, Bureau of Disease Control, Columbia, South Carolina.
3. Division of Infectious Diseases, Department of Medicine, University of South Carolina School of Medicine, Columbia, South Carolina.
4. Department of Epidemiology, Tulane School of Public Health and Tropical Medicine, New Orleans, Louisiana.
5. Mississippi State Department of Health, Jackson, Mississippi.
6. Division of Infectious Diseases, Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi.