A community-wide outbreak of legionnaires disease linked to industrial cooling towers--how far can contaminated aerosols spread?
A community-wide outbreak of legionnaires disease occurred in Pas-de-Calais, France, in November 2003-January 2004. Eighteen (21%) of 86 laboratory-confirmed cases were fatal. A case-control study identified smoking, silicosis, and spending >100 min outdoors daily as risk factors for acquiring the disease. Legionella pneumophila strain Lens was isolated from cooling towers, wastewater, and air samples from plant A. This unique strain matched all 23 clinical isolates, as assessed by pulsed-field gel electrophoresis subtyping. Modeling of atmospheric dispersion of aerosols emitted from plant A cooling towers showed good coverage of the communes where patients lived and showed that the dispersion extended over a distance of at least 6 km from plant A. No other aerosol-producing installation was identified as a plausible source, and no common source of indoor exposure was found. These findings implicate plant A as the most likely outbreak source and suggest that the distance of airborne transmission of L. pneumophila may be greater than previously reported.
Nguyen
Tran Minh Nhu
TM
Institut de Veille Sanitaire and European Programme for Intervention Epidemiology Training, Saint-Maurice, France. nguyen.tran.minh@ktl.fi
Ilef
Daniele
D
Jarraud
Sophie
S
Rouil
Laurence
L
Campese
Christine
C
Che
Didier
D
Haeghebaert
Sylvie
S
Ganiayre
Francois
F
Marcel
Frederic
F
Etienne
Jerome
J
Desenclos
Jean-Claude
JC
D000328:Adult; D000336:Aerosols; D000368:Aged; D000369:Aged, 80 and over; D000389:Air Conditioning; D000391:Air Microbiology; D016022:Case-Control Studies; D004196:Disease Outbreaks; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D007221:Industry; D016952:Legionella pneumophila / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D007877:Legionnaires' Disease / Q000453:epidemiology* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
D000336:Aerosols