title: Epidemiology and estimated costs of a large waterborne outbreak of norovirus infection in Sweden.
abstract: A large outbreak of norovirus (NoV) gastroenteritis caused by contaminated municipal drinking water occurred in Lilla Edet, Sweden, 2008. Epidemiological investigations performed using a questionnaire survey showed an association between consumption of municipal drinking water and illness (odds ratio 4·73, 95% confidence interval 3·53-6·32), and a strong correlation between the risk of being sick and the number of glasses of municipal water consumed. Diverse NoV strains were detected in stool samples from patients, NoV genotype I strains predominating. Although NoVs were not detected in water samples, coliphages were identified as a marker of viral contamination. About 2400 (18·5%) of the 13,000 inhabitants in Lilla Edet became ill. Costs associated with the outbreak were collected via a questionnaire survey given to organizations and municipalities involved in or affected by the outbreak. Total costs including sick leave, were estimated to be ∼8,700,000 Swedish kronor (∼€0·87 million).
authors.affiliation: Department of Communicable Disease Control and Prevention, Region Västra Götaland, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Larsson
authors.affiliation: Swedish Institute for Communicable Disease Control, Solna, Sweden.
authors.forename: Y
authors.initials: Y
authors.lastname: Andersson
authors.affiliation: Swedish Institute for Communicable Disease Control, Solna, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Allestam
authors.affiliation: Department of Communicable Disease Control and Prevention, Region Västra Götaland, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Lindqvist
authors.affiliation: Department of Infectious Diseases/Virology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Sweden.
authors.forename: N
authors.initials: N
authors.lastname: Nenonen
authors.affiliation: Water Environment Technology, Chalmers University of Technology, and Göteborg Vatten, Gothenburg, Sweden.
authors.forename: O
authors.initials: O
authors.lastname: Bergstedt
mesh_terms: D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000821:virology; D004196:Disease Outbreaks; D005243:Feces / Q000821:virology; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology; D006801:Humans; D029322:Norovirus / Q000302:isolation & purification; D011795:Surveys and Questionnaires / Q000191:economics; D013548:Sweden / Q000453:epidemiology; D014871:Water Microbiology; D014881:Water Supply