title: Epidemiological investigation and case-control study: a Legionnaires' disease outbreak associated with cooling towers in Warstein, Germany, August-September 2013.
abstract: Between 1 August and 6 September 2013, an outbreak of Legionnaires' disease (LD) with 159 suspected cases occurred in Warstein, North Rhine-Westphalia, Germany. The outbreak consisted of 78 laboratory-confirmed cases of LD, including one fatality, with a case fatality rate of 1%. Legionella pneumophila, serogroup 1, subtype Knoxville, sequence type 345, was identified as the epidemic strain. A case-control study was conducted to identify possible sources of infection. In univariable analysis, cases were almost five times more likely to smoke than controls (odds ratio (OR): 4.81; 95% confidence interval (CI): 2.33-9.93; p < 0.0001). Furthermore, cases were twice as likely to live within a 3 km distance from one identified infection source as controls (OR: 2.14; 95% CI: 1.09-4.20; p < 0.027). This is the largest outbreak of LD in Germany to date. Due to a series of uncommon events, this outbreak was most likely caused by multiple sources involving industrial cooling towers. Quick epidemiological assessment, source tracing and shutting down of potential sources as well as rapid laboratory testing and early treatment are necessary to reduce morbidity and mortality. Maintenance of cooling towers must be carried out according to specification to prevent similar LD outbreaks in the future.
authors.affiliation: Department of Infectiology and Hygiene, NRW Centre for Health, Münster, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Maisa
authors.forename: Ansgar
authors.initials: A
authors.lastname: Brockmann
authors.forename: Frank
authors.initials: F
authors.lastname: Renken
authors.forename: Christian
authors.initials: C
authors.lastname: Lück
authors.forename: Stefan
authors.initials: S
authors.lastname: Pleischl
authors.forename: Martin
authors.initials: M
authors.lastname: Exner
authors.forename: Inka
authors.initials: I
authors.lastname: Daniels-Haardt
authors.forename: Annette
authors.initials: A
authors.lastname: Jurke
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000389:Air Conditioning; D016022:Case-Control Studies; D017714:Community-Acquired Infections / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D004781:Environmental Exposure / Q000032:analysis; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D016952:Legionella pneumophila / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D007877:Legionnaires' Disease / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D016133:Polymerase Chain Reaction; D012307:Risk Factors; D012703:Serotyping; D012720:Severity of Illness Index; D014871:Water Microbiology; D014881:Water Supply; D055815:Young Adult
keywords: Legionnaires’ disease; cooling towers; outbreak; pneumonia; public health measures