Epidemiology and Infection



An outbreak of calicivirus associated with consumption of frozen raspberries


A. PÖNKÄ a1c1, L. MAUNULA a2, C-H. von BONSDORFF a3 and O. LYYTIKÄINEN a4
a1 Helsinki City Center of the Environment, Helsinginkatu 24, 00530 Helsinki, Finland
a2 Department of Virology, HUCS Diagnostics, Haartmanninkatu 3, 00280, Helsinki, Finland
a3 Department of Virology, Haartman Institute, Haartmanninkatu 3, 00280, Helsinki, Finland
a4 Department of Infectious Disease Epidemiology, National Public Health Institute, Mannenheimintie 166, 00300 Helsinki, Finland

Abstract

In April 1988, an outbreak of gastroenteritis occurred among employees in a large company in Helsinki, Finland. A retrospective cohort study, using a self-administered questionnaire, was carried out to ascertain the cause and extent of the outbreak. To meet the case definition, employees had to have had diarrhoea and/or vomiting since 2 April, 1998. A subanalysis was made in the biggest office, consisting of 360 employees, of whom 204 (57%) completed the questionnaire. Of these 108 (53%) met the case definition. Employees who had eaten raspberry dressing were more likely to meet the case definition than those who had not (Attack Rate (AR) 65% versus AR 18% Relative Risk, (RR) 3·7, 95%, Confidence Intervals (CI) 2·0–6·7). Four stool specimens obtained from affected kitchen staff who had all eaten the raspberry dressing and who had all become ill simultaneously with the employees were positive by polymerase chain reaction (PCR) for calicivirus. The data suggest that the primary source of the outbreak was imported frozen raspberries contaminated by calicivirus.

(Accepted July 20 1999)


Correspondence:
c1 Author for correspondence.


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