1. Department of Medicine and Laboratory Services, Medical University of South Carolina and Ralph H. Johnson VA Medical Center, Charleston, South Carolina
2. Department of Public Health Services, Medical University of South Carolina, Charleston, South Carolina
3. The Biostatistics Center, George Washington University, Washington, D.C.
4. Ralph H. Johnson VA Medical Center, Charleston, South Carolina
5. Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina