1. Istituto Zooprofilattico Sperimentale ‘G. Caporale’; via Campo Boario 64100 Teramo Italy
2. Central Institute for Animal Disease Control Lelystad; PO Box 2004 NL-8203 AA Lelystad The Netherlands
3. Food and Consumer Product Safety (VWA); PO Box 19506 2500 CM Den Haag The Netherlands