a1 Auckland Regional Public Health Service, Auckland District Health Board, Auckland, New Zealand
a2 Institute of Environmental Science and Research Ltd, Porirua, New Zealand
a3 Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
Multiple norovirus outbreaks following catered events in Auckland, New Zealand, in September 2010 were linked to the same catering company and investigated. Retrospective cohort studies were undertaken with attendees of two events: 38 (24·1%) of 158 surveyed attendees developed norovirus-compatible illness. Attendees were at increased risk of illness if they had consumed food that had received manual preparation following cooking or that had been prepared within 45 h following end of symptoms in a food handler with prior gastroenteritis. All food handlers were tested for norovirus. A recombinant norovirus GII.e/GII.4 was detected in specimens from event attendees and the convalescent food handler. All catering company staff were tested; no asymptomatic norovirus carriers were detected. This investigation improved the characterization of norovirus risk from post-symptomatic food handlers by narrowing the potential source of transmission to one individual. Food handlers with gastroenteritis should be excluded from the workplace for 45 h following resolution of symptoms.
(Received May 29 2012)
(Revised December 16 2012)
(Accepted January 09 2013)
(Online publication February 07 2013)