Introduction: In January 2001, 231 persons from the staff of a department in The Netherlands fell sick with diarrhoea and vomiting after a buffet lunch, which was prepared and served at a restaurant. Eighteen restaurant employees also reported illness.
Materials and methods: To determine risk factors for illness a questionnaire was e-mailed to department staff and returned electronically. Employees from the restaurant and the bakery supplying the rolls were interviewed. Stool samples were collected from reported cases and from all the staff of the restaurant and the bakery supplying the rolls. Stools were tested for bacteria and noroviruses.
Results: Analyses of the questionnaires showed an increasing risk of illness with the number of rolls eaten (OR=2.0 95%CI=1.5-2.5). Investigations revealed the baker was suffering from gastroenteritis and had vomited in the bakery sink the day he prepared the rolls. However, he had cleaned up and washed his hands before continuing to work. Norovirus with an identical sequence was detected in the stool samples of ill persons from the department, and symptomatic employees from the restaurant and the bakery.
Conclusion: Foodhandlers are unaware of the potential for transmission of norovirus. Use of electronically mailed questionnaires allowed rapid gathering and analysis of a large amount of data and subsequent identification of the source when detection of virus from the source (the baker) was still possible.