Legionella E-news, April 2000
Matthew R. Freije, Editor
**IN THIS ISSUE**
1. Cooling tower study
2. Recent outbreaks
3. New publications coming soon
1. COOLING TOWER STUDY
Studies by Clive Broadbent have confirmed that biofilm is a primary factor for Legionella growth in cooling towers. Towers having a higher wet-surface-area-to-volume ratio (e.g., because of more piping) were more likely to have high Legionella counts. Biofilm is often released upon startup, so systems that start and stop frequently are especially susceptible to high Legionella counts. (Broadbent, C. "Control of Legionnaires' disease--An Australian Perspective," ASHRAE Transactions 1999, V. 105, Pt. 2)
2. RECENT OUTBREAKS
--Five cases, Melbourne, March 2000, Office building: Five cases of
Legionnaires' disease were reported in Melbourne, Australia. Two of the five individuals work in the same office building on Exhibition Street. The other three cases may also be linked to the Exhibition Street area, according to health officials. High levels of legionellae were found in water samples collected from one of the cooling towers at the 222 Exhibition Street office building. Victoria's Chief Health Officer Dr Graham Rouch urged city dwellers, office workers and visitors to be alert to signs of the disease. Source: Sydney Morning Herald and The Age Online
--Seven cases, Melbourne suburbs, Feb. 2000: Seven people from Fitzroy and Carlton contracted Legionnaires' disease. Chief health officer Graham Rouch said the danger appeared to be in a defined area. "We have to assume, because of this cluster, that we have a community outbreak in that neighborhood," Dr Rouch said. Health officials are testing cooling towers in the area, but have not identified the source. Source:News.com.au
--Hotel, South Wales, Five cases, two deaths, Feb. 2000: Five individuals who acquired Legionnaires' disease each visited the same hotel in South Wales--one in July 1999, one in December 1999, one in January 2000, and two in February 2000. Two of the individuals died of the disease. The hotel's swimming pool, whirlpool spa, plumbing system, and food display humidifier have been investigated, along with cooling towers in the area. Investigators have focused attention on the humidifier, which uses the ultrasonic method to produce aerosols. Source: Eurosurveillance Weekly, reported by Susan Hahné and Roland Salmon, CDSC Wales, Cardiff, Wales and Arun Mukerjee, Bro Taf Health Authority, Cardiff, Wales.
3. NEW PUBLICATIONS COMING SOON
HC Information Resources will soon release new publications addressing the following subjects:
--How to reduce your risk of Legionnaires' disease at home
--How to reduce your risk of Legionnaires' disease in public places
--Guidance for spas, hot tubs, and whirlpool baths
--Dental water lines
We will let you know when the publications are available.
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