Affiliation: | (1) Centre for Epidemiology & Risk Analysis, Veterinary Laboratories Agency, KT15 3NB New Haw, Addlestone, Surrey, UK;(2) Veterinary Laboratories Agency, Langford House, BS40 5DX Langford, Bristol, UK;(3) Centre for Environment, Fisheries and Aquaculture Science, Pakefield Road, NR33 0HT Lowestoft, Suffolk, UK |