title: Association between heavy precipitation events and waterborne outbreaks in four Nordic countries, 1992-2012.
abstract: We conducted a matched case-control study to examine the association between heavy precipitation events and waterborne outbreaks (WBOs) by linking epidemiological registries and meteorological data between 1992 and 2012 in four Nordic countries. Heavy precipitation events were defined by above average (exceedance) daily rainfall during the preceding weeks using local references. We performed conditional logistic regression using the four previous years as the controls. Among WBOs with known onset date (n = 89), exceedance rainfall on two or more days was associated with occurrence of outbreak, OR = 3.06 (95% CI 1.38-6.78), compared to zero exceedance days. Stratified analyses revealed a significant association with single household water supplies, ground water as source and for outbreaks occurring during spring and summer. These findings were reproduced in analyses including all WBOs with known outbreak month (n = 186). The vulnerability of single households to WBOs associated with heavy precipitation events should be communicated to homeowners and implemented into future policy planning to reduce the risk of waterborne illness.
authors.affiliation: Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, Oslo, Norway E-mail: BernardoRafael.Guzman.Herrador@fhi.no.
authors.forename: Bernardo
authors.initials: B
authors.lastname: Guzman Herrador
authors.affiliation: Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, Oslo, Norway E-mail: BernardoRafael.Guzman.Herrador@fhi.no; Oslo Centre for Biostatistics and Epidemiology, Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
authors.forename: Birgitte Freiesleben
authors.initials: BF
authors.lastname: de Blasio
authors.affiliation: Department of Monitoring and Evaluation, Public Health Agency of Sweden, Stockholm, Sweden.
authors.forename: Anneli
authors.initials: A
authors.lastname: Carlander
authors.affiliation: Department of Infectious Disease Epidemiology, Statens Serum Institute, Copenhagen, Denmark.
authors.forename: Steen
authors.initials: S
authors.lastname: Ethelberg
authors.affiliation: Norwegian Meteorological Institute, Oslo, Norway.
authors.forename: Hans Olav
authors.initials: HO
authors.lastname: Hygen
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Markku
authors.initials: M
authors.lastname: Kuusi
authors.affiliation: Department of Food, Water and Cosmetics, Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: Vidar
authors.initials: V
authors.lastname: Lund
authors.affiliation: Department of Monitoring and Evaluation, Public Health Agency of Sweden, Stockholm, Sweden.
authors.forename: Margareta
authors.initials: M
authors.lastname: Löfdahl
authors.affiliation: Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, Oslo, Norway E-mail: BernardoRafael.Guzman.Herrador@fhi.no; European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Emily
authors.initials: E
authors.lastname: MacDonald
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Bath, UK; European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Jaime
authors.initials: J
authors.lastname: Martinez-Urtaza
authors.affiliation: Gastrointestinal, Emerging and Zoonotic Diseases Department, Public Health England, London, UK; Norwich Medical School, University of East Anglia, Norwich, UK; and Department of Hygiene & Epidemiology, University of Thessaly, Thessaly, Greece; European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Gordon
authors.initials: G
authors.lastname: Nichols
authors.affiliation: Department of Monitoring and Evaluation, Public Health Agency of Sweden, Stockholm, Sweden.
authors.forename: Caroline
authors.initials: C
authors.lastname: Schönning
authors.affiliation: European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Sudre
authors.affiliation: Department of Monitoring and Evaluation, Public Health Agency of Sweden, Stockholm, Sweden.
authors.forename: Linda
authors.initials: L
authors.lastname: Trönnberg
authors.affiliation: Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, Oslo, Norway E-mail: BernardoRafael.Guzman.Herrador@fhi.no.
authors.forename: Line
authors.initials: L
authors.lastname: Vold
authors.affiliation: European Centre for Disease Prevention and Control, Stockholm, Sweden.
authors.forename: Jan C
authors.initials: JC
authors.lastname: Semenza
authors.affiliation: Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, Oslo, Norway E-mail: BernardoRafael.Guzman.Herrador@fhi.no.
authors.forename: Karin
authors.initials: K
authors.lastname: Nygård
mesh_terms: D016022:Case-Control Studies; D004196:Disease Outbreaks; D006801:Humans; D011891:Rain; D012537:Scandinavian and Nordic Countries / Q000453:epidemiology; D012914:Snow; D000069578:Waterborne Diseases / Q000453:epidemiology*