1. Clinical Sciences and
2. Food Animal Health and Resource Management, College of Veterinary Medicine, North Carolina State University, Raleigh 27606,
3. Division of Geographic Medicine, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia 22908
4. Department of Pediatrics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599; and
5. Departments of Anatomy, Physiological Sciences, and Radiology,