title: Novel microbiological and spatial statistical methods to improve strength of epidemiological evidence in a community-wide waterborne outbreak.
abstract: Failures in the drinking water distribution system cause gastrointestinal outbreaks with multiple pathogens. A water distribution pipe breakage caused a community-wide waterborne outbreak in Vuorela, Finland, July 2012. We investigated this outbreak with advanced epidemiological and microbiological methods. A total of 473/2931 inhabitants (16%) responded to a web-based questionnaire. Water and patient samples were subjected to analysis of multiple microbial targets, molecular typing and microbial community analysis. Spatial analysis on the water distribution network was done and we applied a spatial logistic regression model. The course of the illness was mild. Drinking untreated tap water from the defined outbreak area was significantly associated with illness (RR 5.6, 95% CI 1.9-16.4) increasing in a dose response manner. The closer a person lived to the water distribution breakage point, the higher the risk of becoming ill. Sapovirus, enterovirus, single Campylobacter jejuni and EHEC O157:H7 findings as well as virulence genes for EPEC, EAEC and EHEC pathogroups were detected by molecular or culture methods from the faecal samples of the patients. EPEC, EAEC and EHEC virulence genes and faecal indicator bacteria were also detected in water samples. Microbial community sequencing of contaminated tap water revealed abundance of Arcobacter species. The polyphasic approach improved the understanding of the source of the infections, and aided to define the extent and magnitude of this outbreak.
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Katri
authors.initials: K
authors.lastname: Jalava
authors.affiliation: Siilinjärvi municipality, Finland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Rintala
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Ollgren
authors.affiliation: Department of Food Hygiene and Environmental Health, University of Helsinki, Helskinki, Finland.
authors.forename: Leena
authors.initials: L
authors.lastname: Maunula
authors.affiliation: Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, United States of America.
authors.forename: Vicente
authors.initials: V
authors.lastname: Gomez-Alvarez
authors.affiliation: Department of Food Hygiene and Environmental Health, University of Helsinki, Helskinki, Finland.
authors.forename: Joana
authors.initials: J
authors.lastname: Revez
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Marja
authors.initials: M
authors.lastname: Palander
authors.affiliation: Laboratory HUSLAB, Helsinki University Hospital, Helsinki, Finland.
authors.forename: Jenni
authors.initials: J
authors.lastname: Antikainen
authors.affiliation: Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland.
authors.forename: Ari
authors.initials: A
authors.lastname: Kauppinen
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Pia
authors.initials: P
authors.lastname: Räsänen
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Sallamaari
authors.initials: S
authors.lastname: Siponen
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Outi
authors.initials: O
authors.lastname: Nyholm
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Aino
authors.initials: A
authors.lastname: Kyyhkynen
authors.affiliation: Siilinjärvi municipality, Finland.
authors.forename: Sirpa
authors.initials: S
authors.lastname: Hakkarainen
authors.affiliation: Siilinjärvi municipality, Finland.
authors.forename: Juhani
authors.initials: J
authors.lastname: Merentie
authors.affiliation: Siilinjärvi municipality, Finland.
authors.forename: Martti
authors.initials: M
authors.lastname: Pärnänen
authors.affiliation: Laboratory HUSLAB, Helsinki University Hospital, Helsinki, Finland.
authors.forename: Raisa
authors.initials: R
authors.lastname: Loginov
authors.affiliation: Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, United States of America.
authors.forename: Hodon
authors.initials: H
authors.lastname: Ryu
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 Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Anja
authors.initials: A
authors.lastname: Siitonen
authors.affiliation: Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland.
authors.forename: Ilkka
authors.initials: I
authors.lastname: Miettinen
authors.affiliation: Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, United States of America.
authors.forename: Jorge W
authors.initials: JW
authors.lastname: Santo Domingo
authors.affiliation: Department of Food Hygiene and Environmental Health, University of Helsinki, Helskinki, Finland.
authors.forename: Marja-Liisa
authors.initials: ML
authors.lastname: Hänninen
authors.affiliation: Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland.
authors.forename: Tarja
authors.initials: T
authors.lastname: Pitkänen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000145:classification / Q000235:genetics; D058491:Bacterial Load; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D060766:Drinking Water / Q000032:analysis / Q000382:microbiology* / Q000821:virology*; D004926:Escherichia coli / Q000235:genetics; D005243:Feces / Q000382:microbiology; D005260:Female; D005387:Finland / Q000453:epidemiology; D005759:Gastroenteritis / Q000453:epidemiology* / Q000382:microbiology / Q000821:virology; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010802:Phylogeny; D012189:Retrospective Studies; D012621:Seasons; D062206:Spatial Analysis; D014871:Water Microbiology; D014876:Water Pollution; D060753:Water Quality; D055815:Young Adult
chemical_list: D060766:Drinking Water