1. Department of Disease Control and Epidemiology; National Veterinary Institute; 751 89 Uppsala Sweden
2. Met Office; FitzRoy Road Exeter EX1 3PB
3. School of Geography; University of Exeter; Exeter EX4 4QZ
4. Institute for Animal Health; Pirbright Laboratory; Ash Road, Pirbright, Woking Surrey GU24 0NF