title: A foodborne outbreak of norovirus gastroenteritis associated with a Christmas dinner in Porto, Portugal, December 2008.
abstract: An outbreak of acute norovirus gastroenteritis was detected and epidemiologically linked to a Christmas dinner reunion of 22 recent graduate students in a restaurant in Porto, Portugal, in December 2008. A retrospective cohort study was carried out using online standardised questionnaires. Sixteen primary and three secondary cases were identified and the risk ratios with 95% confidence intervals for each food item were calculated. The response rate to the online questionnaires was 96%. The outbreak met all four Kaplan s criteria and the attack rate was 73%. Norovirus GII.4 2006b was detected in stools and emesis samples of two primary cases. The ingestion of soup and lettuce salad was considered a risk factor for this norovirus outbreak, as determined by statistical analysis. Our investigation demonstrated two routes of transmission of norovirus starting with foodborne exposure followed by secondary person-to-person spread. To our knowledge this is the first study identifying norovirus as the causative agent of a foodborne outbreak in Portugal.
authors.affiliation: Department of Microbiology, Faculty of Pharmacy, University of Porto, Portugal.
authors.forename: J R
authors.initials: JR
authors.lastname: Mesquita
authors.forename: M S J
authors.initials: MS
authors.lastname: Nascimento
mesh_terms: D000328:Adult; D017250:Caliciviridae Infections / Q000453:epidemiology*; D004196:Disease Outbreaks; D005260:Female; D005517:Foodborne Diseases / Q000453:epidemiology*; D005759:Gastroenteritis / Q000453:epidemiology*; D006801:Humans; D008297:Male; D029322:Norovirus; D011174:Portugal / Q000453:epidemiology