[1] Natl Vet Inst, Swedis Zoonosis Ctr, Dept Bacteriol, S-75189 Uppsala, Sweden
[2] Natl Food Adm Toxicol Lab, SE-75126 Uppsala, Sweden
[3] Swedish Board Agr, SE-55182 Jonkoping, Sweden
[4] Swedish Poultry Meat Assoc, SE-10214 Stockholm, Sweden
[5] Swedish Inst Infect Dis Control, SE-17182 Solna, Sweden