1. From the Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, the Blood Bank, Clinical Center, National Institutes of Health, Bethesda, MD and Louisiana State University Medical Center, New Orleans, LA (address reprint requests to Dr. Miller at the Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bldg. 5, Room 114, National Institutes of Health, Bethesda, MD 20014).