1. Wildlife and Emerging Diseases Section; Royal (Dick) School of Veterinary Medicine; University of Edinburgh; Easter Bush Roslin Midlothian EH25 9RG
2. Department of Ecology and Evolutionary Biology; Princeton University; Princeton NJ 08544 USA
3. Centre for Infectious Diseases; University of Edinburgh; Ashworth Laboratories; Kings Buildings, West Mains Road Edinburgh EH9 3JF