[1] Univ Liege, Fac Vet Med, Dept Food Sci, Microbiol Sect, B-4000 Liege, Belgium
[2] Univ Liege, Fac Vet Med, Dept Infect & Parasit Dis, B-4000 Liege, Belgium
[3] Univ Liege, Fac Vet Med, Dept Anim Prod, B-4000 Liege, Belgium
[4] Univ Ghent, Fac Vet Med, Vet Epidemiol Unit, Dept Reprod Obstet & Herd Hlth, B-9820 Merelbeke, Belgium
[5] Inst Agr & Fisheries Res, Technol & Food Unit, B-9090 Melle, Belgium
[6] Univ Ghent, Fac Vet Med, Dept Vet Publ Hlth & Food Safety, B-9820 Merelbeke, Belgium