1. Department of Environmental Health Science, University of Georgia, 150 Green St., Athens, Georgia 30602, USA
2. Department of Infectious Diseases, University of Georgia, 111 Carlton St., Athens, Georgia 30602, USA
3. Department of Pathology, University of Georgia, 501 D. W. Brooks Dr., Athens, Georgia 30602, USA
4. Department of Anatomy and Radiology, University of Georgia, 111 Carlton St., Athens, Georgia 30602, USA