1. Ecology and Epidemiology Group, Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
2. Department of Veterinary Microbiology and Parasitology, University College Dublin, Belfield, Dublin 4, Ireland
3. Institute of Zoology, Ministry of the Environment, Akademgorodok, Almaty, Kazakhstan
4. Institute of Parasitology, University of Zürich, Winterthurerstrasse 266a, CH-8057, Zürich, Switzerland
5. Renewable Resources Assessment Group, Department of Environmental Science and Technology, Imperial College London, SW7 2AZ, UK