Two outbreaks of norovirus infections associated with the consumption of imported frozen raspberries, Denmark, May-June 2005

Publié le 1 Avril 2005
Mis à jour le 5 juillet 2019

On the weekend of 21-22 May, it was reported that 101 patients and 76 employees at the two Aalborg Hospitals, South and North, in Nothern Jutland, were ill with vomiting and diarrhoea. In the following four days, a further 43 patients and 52 employees, as well as 4 relatives, were reported to be ill. Because of simultaneous outbreaks in the two physically separated hospitals, a foodborne source of infection was suspected. Cohort isolation of the sick patients was implemented, and some admissions, as well as a total of 43 operations, were cancelled. Sick employees were requested not to turn up for work until they had been well for at least 24 hours (48 hours for kitchen staff). In order to reduce the risk of infection, kitchen areas were disinfected and cleaning staff were instructed in disinfection of toilet areas. Infection control nurses and the Regional Food Inspectorate provided disinfection guidelines, for which a disinfectant that is active against norovirus was used. Case-control studies were conducted among a total of 120 employees and inpatients at the hospitals. The studies showed that the sick employees had all been at work on Thursday (odds ratio (OR) 15; 95% confidence interval (CI) 3.4 to 71) and that the consumption of a "fromage blanc" (fresh cheese) dessert containing frozen pieces of raspberries in the canteen that day was associated with an increased risk of disease (OR infinite, lower CI 3.4). Consumption of the same dessert with raspberries was also associated with illness in patients (OR 6.2; 95% CI 1.6 to 26). The suspicion of a norovirus infection was confirmed by the results of investigation of faecal specimens. (Introduction)

Auteur : Korsager B, Hede S, Boggild H, Bottiger B, Molbak K
Eurosurveillance. European communicable disease quarterly, 2005, vol. 10, n°. 4-6, p. p. 129