1. Centre for Complexity Science, University of Warwick, Coventry CV4 7AL, UK
2. School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington LE12 5RD, UK
3. Central Veterinary Institute, Wageningen UR (CVI), PO Box 65, 8200 AB Lelystad, The Netherlands
4. School of Social and Community Medicine, University of Bristol, Bristol BS8 2BN, UK
5. Fogarty International Center, US National Institute of Health, Bethesda, MD 20892, USA