1. Epidemiology Unit, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
2. United States Public Health Service, Commissioned Corps, Rockville, Maryland
3. Critical Care Medicine Department, National Institutes of Health Clinical Center, Maryland
4. Internal Medicine Consult Service, National Institutes of Health Clinical Center, Bethesda, Maryland