Institution: | 1. Department of Mathematics and Statistics, Murray State University, Murray KY 42071, E‐mail: dadongo@murraystate.edu;2. Department of Mathematics and Statistics, Murray State University, Murray KY 42071, E‐mail: kfister@murraystate.edu;3. Department of Biological Sciences, Old Dominion University, Norfolk VA 23529 E‐mail: hgaff@odu.edu;4. Department of Microbiology and Immunology, Georgetown University Medical Center, Washington DC 20057 and Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, E‐mail: dh268@georgetown.edu |