We would like to thank Dr. Andrew Hudson (Christchurch Science Centre) for his significant contributions to the planning of this study and for his editorial input, Dr. Rob Crawford (Fonterra) for the development of the modified MPN method used in this study and also the contributions made to the design and execution of the study by Dr. Steve Hathaway, Dr. Roger Cook and Dr. Lisa Oakley (NZFSA), Dr. Fiona Thompson-Carter (Environmental Science and Research), Dr. Nigel French (Massey University), Warwick Aspin (AsureQuality) and Sally Miller (Fonterra Research Centre). We also recognise the important contribution of the Fonterra milk collection staff who ensured that the required samples were collected, chilled and couriered to the analytical laboratory throughout the study.