Affiliation: | a Department of Pathology and Epidemiology, Danish Veterinary Laboratory, 27 Bülowsvej, DK-1790 Copenhagen V., Denmark b Department of Animal Science and Animal Health and Department of Clinical Studies, Royal Veterinary and Agricultural University, 17 Bülowsvej, DK-1870 Frederiksberg C., Denmark c Danish Bacon and Meat Council, 3 Axeltorv, DK-1609 Copenhagen V., Denmark |