title: A controlled survey of less typical long-term consequences after an extensive waterborne epidemic.
abstract: Extensive backflow of treated wastewater caused household water contamination in a Finnish town in 2007. The drinking water of 9 500 residents became heavily polluted with faecal microbes, resulting in a large gastroenteritis epidemic. Cases of reactive arthritis, milder joint symptoms and prolonged gastrointestinal symptoms were observed after the outbreak. A follow-up survey was performed to study less familiar long-term health consequences within a year from the outbreak.
  
  
  
  The contaminated group comprised a sample of residents of the area with polluted water supply (N = 323) and the control group a sample of residents in a nearby municipality (N = 186). The presence of 20 general symptoms or complaints was inquired by a mail survey. Quarterly prevalence of each symptom or complaint was measured. Twelve of these proceeded to further analysis.
  
  
  
  The response rate was 53% (323/615) in the contaminated group and 54% (186/343) in the control group. Rash, eye irritation, heartburn and weight loss were more prevalent in the contaminated group during the first year quarter. In the last year quarter, only eye irritation was significantly more common in the contaminated group.
  
  
  
  The excess prevalence of four complaints at the first year quarter can be explained by acute gastroenteritis or intensive water chlorination. The excess prevalence of eye irritation at the fourth year quarter cannot be explained by chlorination anymore but might be a sign of co-existing reactive joint disease. In general, long-term consequences of the outbreak can be considered minor in terms of the surveyed symptoms or complaints.
authors.affiliation: Department of Internal Medicine, Tampere University Hospital, P.O. Box 2000, 33521, Tampere, Finland. janne.laine@pshp.fi.|National Institute of Health and Welfare, Helsinki, Finland. janne.laine@pshp.fi.
authors.forename: Janne
authors.initials: J
authors.lastname: Laine
authors.affiliation: Department of Internal Medicine, Tampere University Hospital, P.O. Box 2000, 33521, Tampere, Finland.|School of Medicine, University of Tampere, Tampere, Finland.
authors.forename: Outi
authors.initials: O
authors.lastname: Laine
authors.affiliation: School of Medicine, University of Tampere, Tampere, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Lumio
authors.affiliation: Department of Internal Medicine, Tampere University Hospital, P.O. Box 2000, 33521, Tampere, Finland.
authors.forename: Jaakko
authors.initials: J
authors.lastname: Antonen
authors.affiliation: National Institute of Health and Welfare, Helsinki, Finland.
authors.forename: Salla
authors.initials: S
authors.lastname: Toikkanen
authors.affiliation: National Institute of Health and Welfare, Helsinki, Finland.
authors.forename: Mikko J
authors.initials: MJ
authors.lastname: Virtanen
authors.affiliation: National Institute of Health and Welfare, Helsinki, Finland.
authors.forename: Markku
authors.initials: M
authors.lastname: Kuusi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D060766:Drinking Water / Q000009:adverse effects* / Q000382:microbiology; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D005759:Gastroenteritis / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D006306:Health Surveys; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011795:Surveys and Questionnaires; D062065:Wastewater; D014871:Water Microbiology; D014876:Water Pollution / Q000009:adverse effects*; D000069578:Waterborne Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D055815:Young Adult
chemical_list: D060766:Drinking Water; D062065:Wastewater
keywords: Epidemics; Gastroenteritis; General symptoms; Outcome; Waterborne infections