title: An outbreak of Campylobacter jejuni associated with consumption of chicken, Copenhagen, 2005.
abstract: In May/June 2005 an outbreak of diarrhoeal illness occurred among company employees in Copenhagen. Cases were reported from seven of eight companies that received food from the same catering kitchen. Stool specimens from three patients from two companies were positive for Campylobacter jejuni. We performed a retrospective cohort study among employees exposed to canteen food in the three largest companies to identify the source of the outbreak and to prevent further spread. Using self-administered questionnaires we collected information on disease, days of canteen food eaten and food items consumed. The catering kitchen was inspected and food samples were taken. Questionnaires were returned by 295/348 (85%) employees. Of 247 employees who ate canteen food, 79 were cases, and the attack rate (AR) was 32%. Consuming canteen food on 25 May was associated with illness (AR 75/204, RR=3.2, 95%CI 1.3-8.2). Consumption of chicken salad on this day, but not other types of food, was associated with illness (AR=43/97, RR=2.3, 95%CI 1.3-4.1). Interviews with kitchen staff indicated the likelihood of cross-contamination from raw chicken to the chicken salad during storage. This is the first recognised major Campylobacter outbreak associated with contaminated chicken documented in Denmark. It is plausible that food handling practices contributed to transmission, and awareness of safe food handling and storage has since been raised among kitchen staff. The low number of positive specimens accrued in this outbreak suggests a general underascertainment of adult cases in the laboratory reporting system by a factor of 20.
authors.affiliation: European Programme for Intervention Epidemiology Training (EPIET), Department of Epidemiology, Statens Serum Institut, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Mazick
authors.forename: S
authors.initials: S
authors.lastname: Ethelberg
authors.forename: E Møller
authors.initials: EM
authors.lastname: Nielsen
authors.forename: K
authors.initials: K
authors.lastname: Mølbak
authors.forename: M
authors.initials: M
authors.lastname: Lisby
mesh_terms: D000818:Animals; D002169:Campylobacter Infections / Q000453:epidemiology* / Q000382:microbiology; D016123:Campylobacter jejuni / Q000302:isolation & purification*; D002645:Chickens / Q000382:microbiology; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D005506:Food Contamination / Q000706:statistics & numerical data*; D005517:Foodborne Diseases / Q000453:epidemiology* / Q000382:microbiology; D005759:Gastroenteritis / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D015994:Incidence; D008460:Meat / Q000382:microbiology; D011159:Population Surveillance; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors