title: A large outbreak of Legionnaires' disease at a flower show, the Netherlands, 1999.
abstract: In 1999, an outbreak of Legionnaires' disease affected many visitors to a flower show in the Netherlands. To identify the source of the outbreak, we performed an environmental investigation, as well as a case-control study among visitors and a serologic cohort study among exhibitors to measure exposure to possible sources. Of 77,061 visitors, 188 became ill (133 confirmed and 55 probable cases), for an attack rate of 0.23% for visitors and 0.61% for exhibitors. Two whirlpool spas in halls 3 and 4 of the exhibition and a sprinkler in hall 8 were culture positive for Legionella pneumophila. One of three genotypes found in both whirlpool spas was identical to the isolates from 28 of 29 culture-positive patients. Persons who paused at the whirlpool spa in hall 3 were at increased risk for becoming ill. This study illustrates that whirlpool spas may be an important health hazard if disinfection fails.
authors.affiliation: National Institute of Public Health and the Environment, Bilthoven, the Netherlands. jwdenboer.ggdhaarlem@wxs.nl
authors.forename: Jeroen W
authors.initials: JW
authors.lastname: Den Boer
authors.forename: Ed P F
authors.initials: EP
authors.lastname: Yzerman
authors.forename: Joop
authors.initials: J
authors.lastname: Schellekens
authors.forename: Kamilla D
authors.initials: KD
authors.lastname: Lettinga
authors.forename: Hendriek C
authors.initials: HC
authors.lastname: Boshuizen
authors.forename: Jim E
authors.initials: JE
authors.lastname: Van Steenbergen
authors.forename: Arnold
authors.initials: A
authors.lastname: Bosman
authors.forename: Susan
authors.initials: S
authors.lastname: Van den Hof
authors.forename: Hans A
authors.initials: HA
authors.lastname: Van Vliet
authors.forename: Marcel F
authors.initials: MF
authors.lastname: Peeters
authors.forename: Ruud J
authors.initials: RJ
authors.lastname: Van Ketel
authors.forename: Peter
authors.initials: P
authors.lastname: Speelman
authors.forename: Jacob L
authors.initials: JL
authors.lastname: Kool
authors.forename: Marina A E
authors.initials: MA
authors.lastname: Conyn-Van Spaendonck
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D016022:Case-Control Studies; D015331:Cohort Studies; D004196:Disease Outbreaks; D005260:Female; D005838:Genotype; D006801:Humans; D006875:Hydrotherapy; D016952:Legionella pneumophila / Q000145:classification / Q000276:immunology* / Q000302:isolation & purification; D007877:Legionnaires' Disease / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D018570:Risk Assessment; D016036:Seroepidemiologic Studies
chemical_list: D000907:Antibodies, Bacterial