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Editor—Joseph underlines the paradox of larger outbreaks of legionnaires' disease when understanding of causality is greater than ever.1 She gives four explanations—loss of vigilance in maintenance of water systems, greater clinical awareness, better surveillance, and easier diagnosis. She calls for enhanced surveillance of both sporadic disease and outbreaks and for greater vigilance in control. Some lessons from studies of legionnaires' disease in Scotland are pertinent to concerns fuelled by outbreaks in England this summer.
In Glasgow a survey conducted after two outbreaks, including the largest in the United Kingdom up to 1984, showed up difficulties in maintaining an accurate register of cooling towers, poor understanding among some managers of premises about the nature and location of cooling towers and evaporative condensers, and breaches of guidelines, usually on structural issues—for example, control of the drift of cooling towers rather than non-use of chemicals.2 The problems would have been even greater without the publicity of the preceding outbreaks. Breaches of guidelines on the maintenance of hot water systems were also of concern and constituted a hazard for legionnaires' disease.3
Apparently sporadic cases were often part of mini-clusters.4 The conclusion, anticipating that of Joseph, was that surveillance needed strengthening and that solitary cases needed investigation promptly for potential early warning of an outbreak. Information crucial to surveillance—address, postcode, and date of onset—was often missing from laboratory request forms, which contribute to surveillance. Clinicians must understand why such information is needed so they are motivated to provide it.
Studies of sporadic disease suggested the sources of infection were similar to those for outbreaks, for the epidemiological patterns were similar, with proximity of the home to a cooling tower being a risk factor.5
The costs of maintaining water systems—both financially and in terms of environmental contamination—are high, so choices need to be made. Preliminary economic analysis showed the emphasis needs to be placed on maintenance of cooling towers rather than domestic water systems, but more work is needed on this.
Elimination of legionnaires' disease is not achievable, so vigilance combined with a balanced response based on an understanding of costs and benefits is required—neither panic nor media pressure should drive priorities. These lessons based on studies in the 1980s remain relevant to understanding and controlling the outbreaks that have gripped the nation.
1.Joseph C. New outbreak of legionnaires′ disease in the United Kingdom. BMJ. 2002;325:347–348. doi: 10.1136/bmj.325.7360.347. . (17 August.) [DOI] [PMC free article] [PubMed] [Google Scholar]
2.Bhopal RS, Barr G. Maintenance of cooling towers following two outbreaks of legionnaires′ disease in a city. Epidemiol Infect. 1990;104:29–38. doi: 10.1017/s0950268800054492. [DOI] [PMC free article] [PubMed] [Google Scholar]
3.Bhopal RS, Barr G. Are hot and cold water systems maintained in accord with published guidelines? A preliminary answer. Health Hygiene. 1991;12:159–165. [Google Scholar]
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BMJ. 2002 Nov 2;325(7371):1033.
Official cleaning and disinfection procedures must be adhered to
Editor—I have already reported a large outbreak of legionnaires′ disease in Japan, but would like to add new information after reading the editorial by Joseph.1-1,1-2
According to the latest official announcement by Hyuga City, 294 (158 men and 136 women) became ill (29 confirmed and 265 probable cases), and six people (four men and two women over 60 years old) died. All had visited the same hot-spring resort in Hyuga City and had been bathing in spas contaminated with Legionella pneumophila. The facility was found not to have followed health ministry procedures for cleaning and disinfection in spa and public bath facilities.
Most Japanese people are fond of bathing in hot springs, but substandard cleaning methods at spa and public bath facilities nationwide are putting patrons at risk from potentially lethal microorganisms.1-3 Scientists at the National Institute of Infectious Diseases found amoebas at 151 (64%) of the 237 facilities they tested. In 2000 another large outbreak of legionnaires' disease occurred at a municipal public bath in Ishioka City in Ibaraki Prefecture. Three people died, and in 42 other people the disease was diagnosed. The facility had seldom exchanged recirculated hot water of the public bath. The importance of following ministry established cleaning and disinfection procedures to the letter should be emphasised.
1-2.Joseph C. New outbreak of legionnaires′ disease in the United Kingdom. BMJ. 2002;325:347–348. doi: 10.1136/bmj.325.7360.347. . (17 August.) [DOI] [PMC free article] [PubMed] [Google Scholar]
1-3. Anonymous. Report: Onsen hygiene lacking. International Herald Tribune/Asahi Shimbun 2002; Aug 16:22.
BMJ. 2002 Nov 2;325(7371):1033.
Extracorporeal membrane oxygenation should be considered in severe cases
Editor—The sudden influx of around 92 patients, with 19 admissions to intensive care, in the recent outbreak of legionella pneumonia in Cumbria2-1 is a notable strain on any health service.
The number of reported cases of legionella infection in the United Kingdom has increased steadily from 147 in 1993 to 226 in 1998.2-2,2-3 As Joseph says, legionnaires' disease is often underdiagnosed and sporadic; only severe illness is detected and reported. The most seriously affected patients develop fulminant respiratory and multisystem failure, and this is the main cause of death for the 10-15% who die.2-1,2-4
We have used extracorporeal membrane oxygenation in 16 adult patients with the most severe form of legionella infection between 1989 and 2001. Their modal ratio of pulmonary artery oxygen content to fractional inspired oxygen ratio before oxygenation was 8.7 kPa (range 4.1-27.1 kPa), 13 were male, and their mean age was 43 years (SD 10.6). They all received venovenous extracorporeal membrane oxygenation for a mean time of 258 hours (SD 235 hours).
Survival to hospital discharge was 69%, with 11 of the 16 patients surviving at six months. This is similar to the 66% survival that we have reported for adult patients with a variety of respiratory diagnoses.2-5
All extracorporeal membrane oxygenation of adults in the United Kingdom now falls within the remit of the CESAR trial (www.cesar-trial.org). To be eligible for the trial, patients must be aged between 18 and 65, have a Murray lung injury score of >3.0 and a duration of high pressure or high oxygen ventilation of <7 days. We recommend that any patients with severe legionella infection who are deteriorating despite optimal conventional intensive care should be considered for the CESAR trial.
Footnotes
On behalf of G J Peek, N Roberts, C Harvey, A W Sosnowski, H M Killer, R K Firmin (Glenfield Hospital); D Jenkins (Leicester General Hospital); and A Truesdale, D Elbourne (London School of Hygiene and Tropical Medicine).
References
2-1.Joseph C. New outbreak of legionnaires' disease in the United Kingdom. BMJ. 2002;325:347–348. doi: 10.1136/bmj.325.7360.347. . (17 August.) [DOI] [PMC free article] [PubMed] [Google Scholar]
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