title: Gastro-enteritis outbreak among Nordic patients with psoriasis in a health centre in Gran Canaria, Spain: a cohort study.
abstract: BACKGROUND
  Between November 2 and 10, 2002 several patients with psoriasis and personnel staying in the health centre in Gran Canaria, Spain fell ill with diarrhoea, vomiting or both. Patient original came from Norway, Sweden and Finland. The patient group was scheduled to stay until 8 November. A new group of patients were due to arrive from 7 November.
  
  
  METHODS
  A retrospective cohort study was conducted to assess the extent of the outbreak, to identify the source and mode of transmission and to prevent similar problems in the following group.
  
  
  RESULTS
  Altogether 41% (48/116) of persons staying at the centre fell ill. Norovirus infection was suspected based on clinical presentations and the fact that no bacteria were identified. Kaplan criteria were met. Five persons in this outbreak were hospitalised and the mean duration of diarrhoea was 3 days. The consequences of the illness were more severe compared to many other norovirus outbreaks, possibly because many of the cases suffered from chronic diseases and were treated with drugs reported to affect the immunity (methotrexate or steroids). During the two first days of the outbreak, the attack rate was higher in residents who had consumed dried fruit (adjusted RR = 3.1; 95% CI: 1.4-7.1) and strawberry jam (adjusted RR = 1.9; 95% CI: 0.9-4.1) than those who did not. In the following days, no association was found. The investigation suggests two modes of transmission: a common source for those who fell ill during the two first days of the outbreak and thereafter mainly person to person transmission. This is supported by a lower risk associated with the two food items at the end of the outbreak.
  
  
  CONCLUSIONS
  We believe that the food items were contaminated by foodhandlers who reported sick before the outbreak started. Control measures were successfully implemented; food buffets were banned, strict hygiene measures were implemented and sick personnel stayed at home >48 hours after last symptoms.
authors.affiliation: European Programme for Intervention Epidemiology Training, Stocholm, Sweden. hanne.merete.eriksen@fhi.no
authors.forename: Hanne M
authors.initials: HM
authors.lastname: Eriksen
authors.forename: Philippe J
authors.initials: PJ
authors.lastname: Guerin
authors.forename: Karin
authors.initials: K
authors.lastname: Nygård
authors.forename: Marika
authors.initials: M
authors.lastname: Hjertqvist
authors.forename: Birgitta
authors.initials: B
authors.lastname: de Jong
authors.forename: Angela M C
authors.initials: AM
authors.lastname: Rose
authors.forename: Markku
authors.initials: M
authors.lastname: Kuusi
authors.forename: Ulrike
authors.initials: U
authors.lastname: Durr
authors.forename: A G
authors.initials: AG
authors.lastname: Rojas
authors.forename: Cato
authors.initials: C
authors.lastname: Mør
authors.forename: Preben
authors.initials: P
authors.lastname: Aavitsland
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001266:Atlantic Islands / Q000453:epidemiology; D017250:Caliciviridae Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D015331:Cohort Studies; D003967:Diarrhea; D004196:Disease Outbreaks; D005260:Female; D005517:Foodborne Diseases / Q000453:epidemiology* / Q000209:etiology; D005759:Gastroenteritis / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D006268:Health Facilities; D006801:Humans; D008297:Male; D008875:Middle Aged; D029322:Norovirus; D011565:Psoriasis / Q000150:complications* / Q000628:therapy; D012189:Retrospective Studies; D012537:Scandinavian and Nordic Countries / Q000208:ethnology; D013030:Spain / Q000453:epidemiology; D011795:Surveys and Questionnaires; D014839:Vomiting