1Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Agnes Sjöberginkatu 2, PO Box 66, 00790, Helsinki, Finland
2Expert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare, Mannerheimintie 166, PO Box 30, 00271, Helsinki, Finland
3Korkeasaari Zoo, Mustikkamaanpolku 12, PO Box 1000, 0081 Helsinki, Finland
4Microbiology Unit, Finnish Food Authority, Mustialankatu 3, PO Box 200, 00790 Helsinki, Finland