1. Division of Foodborne, Bacterial and Mycotic Diseases, National Center for Zoonotic, Vectorborne and Enteric Diseases; Centers for Disease Control and Prevention; 1600 Clifton Road, Mailstop C-09 Atlanta GA 30333
2. University of Manchester, Clinical Sciences Building; Hope Hospital, Stott Lane, Salford M6 8HD United Kingdom
3. OzFoodNet, Office of Health Protection; Department of Health and Ageing; GPO Box 9848, MDP 14, Canberra 2601 Australian Capital Territory Australia