Epidemic Legionnaires' disease. Airborne transmission down a chimney.
Between June 18 and July 9, 1979, Legionnaires' disease (LD) developed in 13 persons who had visited a hotel complex in Wisconsin. All had visited the part of the hotel that contains the restaurants and meeting rooms (building A). Legionnaires' disease occurred in 1% who had been exclusively in the meeting rooms and in 0.1% who had eaten only at the hotel restaurants. Furthermore, 1.5% exposed to meeting room 1 and none of those exposed only to the other meeting rooms had LD. Legionella pneumophila was isolated from water in the cooling tower on top of building A. Located within 5 m downwind of the cooling-tower exhaust, a chimney with an open damper allowed cooling-tower exhaust (as demonstrated by air tracer studies) to enter meeting room 1 via the fireplace. Although cases did not occur after the cooling-tower water was treated by continuous hyperchlorination and the chimney was sealed, a seven-day lag occurred between treatment and elimination of the organism from the tower water.
D000368:Aged; D000389:Air Conditioning / Q000295:instrumentation; D000391:Air Microbiology; D004196:Disease Outbreaks; D004197:Disease Reservoirs; D005260:Female; D006801:Humans; D007875:Legionella / Q000302:isolation & purification; D007877:Legionnaires' Disease / Q000635:transmission*; D008297:Male; D012621:Seasons; D014871:Water Microbiology; D014922:Wisconsin