"Legionella: - 30 Years On" International Conference
Short Report on the WMSOC/SCI/RSC "Legionella: - 30 Years On" International Conference held on 12-13 June 2006 at the National Motorcycle Museum, Birmingham
The first day gave a global view of Legionella with details of a number of major outbreaks in the UK; Spain, the Netherlands and a UK hospital. All these presentations stressed the lessons learnt from each of these outbreaks. The outbreak in Spain was the biggest ever reported with 449 confirmed cases with (~800 suspected cases in total). The Dutch flower show outbreak infected more than 200 people infected with more than 30 deaths.
The second day continued on this theme with an Australian viewpoint and then went on to consider treatment processes and strategies; issues associated with spa baths; Legionella water analysis developments (it is now possible to obtain a result within three hours of receiving a sample); future research needs and the conference concluded with a comprehensive presentation from Steve Copping of the HSE entitled “The future direction of legislation”.
The following information was presented: -
In Australia approximately one half of Legionella infections originate from potting compost. Consequently all potting composts have Legionella warnings on the bag. Also most cooling tower incidents in Australia are associated with the smaller cooling towers of less than 500 kW. The five categories of risk factors were cited as: - stagnant water; nutrient availability; poor system water system; deficiencies in the cooling water system and location and access aspects of cooling towers.
The initial first recorded 1976 outbreak in Philadelphia resulted in 200 cases with 13 deaths. It took six months to ascertain the cause as Legionella. Evidence from preserved lung tissue has shown that Legionella outbreaks had occurred as far back as 1944 and this would indicate that the disease had occurred way before this, but had not been diagnosed as such.
Currently in the UK, Legionella is not a notifiable disease
For the normal population the disease has a 10 -12% fatality rate. For hospital patients the fatality rate is 30 – 40% because of suppression of the immune system for ill individuals. Consequently water management in health premises is probably on of the biggest risks especially when commissioning new hospitals or from an area of the hospital where the water system has not been in use for some time. It was pointed out that in the last five years the use of alcohol based disinfectant hand gels in hospitals has increased dramatically. This has led to less hand washing and has resulted in underused taps (especially mixer taps) which encourage the proliferation of Legionella bacteria.
Legionella infection can also express as Pontiac Fever which is a flu-like illness rather than the classic pneumonia-like illness. This former illness although unpleasant is never fatal. The reason for this difference in the two modes of infection is still being investigated.
Legionella bacteria are very widespread in the environment in soils, waste and waters. Low levels have even been detected in some mains tap water samples.
Evidence was presented that infection could be transmitted up to 8 km from a badly infected cooling tower under ideal weather transmission conditions.
To avoid outbreaks it is essential that when designing new premises that architects, engineers, chemists and microbiologists liaise and once any water systems are commissioned a robust maintenance plan is instituted with an associated robust system of records demonstrating fit for purpose on-going maintenance. Also the importance of good training of all maintenance staff was stressed by a number of speakers.
The conference proceedings are now available from RSC Publications to buy those now follow the link on the right of this article
K. Clive Thompson
24 June 2006
