1. Center for Infectious Disease Dynamics, Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
2. Fogarty International Center, National Institutes of Health, Bethesda, Maryland 20892
3. The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, 5668 State Farm Rd., Slingerlands, New York 12159
4. Department of Biomedical Sciences, School of Public Health, The University at Albany, State University of New York, Albany, New York 12144-3456
5. Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131