title: Epidemiological and serological investigation of a waterborne Campylobacter jejuni outbreak in a Danish town.
abstract: Following an unusually heavy rainfall in June 2009, a community-wide outbreak of Campylobacter gastroenteritis occurred in a small Danish town. The outbreak investigation consisted of (1) a cohort study using an e-questionnaire of disease determinants, (2) microbiological study of stool samples, (3) serological study of blood samples from cases and asymptomatic members of case households, and (4) environmental analyses of the water distribution system. The questionnaire study identified 163 cases (respondent attack rate 16%). Results showed a significant dose-response relationship between consumption of tap water and risk of gastroenteritis. Campylobacter jejuni belonging to two related flaA types were isolated from stool samples. Serum antibody levels against Campylobacter were significantly higher in cases than in asymptomatic persons. Water samples were positive for coliform bacteria, and the likely mode of contamination was found to be surface water leaking into the drinking-water system. This geographically constrained outbreak presented an ideal opportunity to study the serological response in persons involved in a Campylobacter outbreak. The serology indicated that asymptomatic persons from the same household may have been exposed, during the outbreak period, to Campylobacter at doses that did not elicit symptoms or alternatively had been exposed to Campylobacter at a time prior to the outbreak, resulting in residual immunity and thus absence of clinical signs.
authors.affiliation: Department of Infectious Disease Epidemiology,Statens Serum Institut,Copenhagen,Denmark.
authors.forename: K Gaardbo
authors.initials: KG
authors.lastname: Kuhn
authors.affiliation: Department for Infectious Disease Epidemiology,Robert Koch Institute,Berlin,Germany.
authors.forename: G
authors.initials: G
authors.lastname: Falkenhorst
authors.affiliation: Department of Infectious Disease Epidemiology,Statens Serum Institut,Copenhagen,Denmark.
authors.forename: H-D
authors.initials: HD
authors.lastname: Emborg
authors.affiliation: Department of Microbiological Diagnostics and Virology,Statens Serum Institut,Copenhagen,Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Ceper
authors.affiliation: Department of Microbiology and Infection Control,Statens Serum Institut,Copenhagen,Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Torpdahl
authors.affiliation: Department of Microbiology and Infection Control,Statens Serum Institut,Copenhagen,Denmark.
authors.forename: K A
authors.initials: KA
authors.lastname: Krogfelt
authors.affiliation: Department of Infectious Disease Epidemiology,Statens Serum Institut,Copenhagen,Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Ethelberg
authors.affiliation: Department of Infectious Disease Epidemiology,Statens Serum Institut,Copenhagen,Denmark.
authors.forename: K
authors.identifier: 0000-0002-3100-4990
authors.initials: K
authors.lastname: Mølbak
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood; D002169:Campylobacter Infections / Q000453:epidemiology*; D016123:Campylobacter jejuni / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D004196:Disease Outbreaks; D005243:Feces / Q000382:microbiology; D005260:Female; D005408:Flagellin / Q000235:genetics; D005759:Gastroenteritis / Q000453:epidemiology*; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D011795:Surveys and Questionnaires; D014871:Water Microbiology; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D005408:Flagellin; C067138:flaA protein, bacteria
keywords: 
                 Campylobacter
              ; cohort study; outbreak; serology; waterborne