1. Department of Medicine, Division of Infectious Diseases, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania 15261.
2. Department of Microbiology and Immunology, East Carolina University, School of Medicine, Greenville, North Carolina 27858.
3. Department of Prospective Health, East Carolina University, School of Medicine, Greenville, North Carolina 27858.
4. Honors Medical Program, East Carolina University, School of Medicine, Greenville, North Carolina 27858.