Abstract
1 Department of Veterinary Pathology, Veterinary Field Station, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, United Kingdom
3 Centre for Tropical Veterinary Medicine, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, United Kingdom
2 Division of Comparative Medicine, University of Minnesota Medical School, Minneapolis, Minnesota 55455
4 Department of Biology, Institute for Molecular and Cellular Biology, Indiana University, Bloomington, Indiana 47405