Legionnaires’ Disease - Assessing the Risks

Legionnaires’ Disease - This short paper reviews issues that surround the subjects of Legionella and Legionnaires’ disease and in particular, those members of the population that are most susceptible to the disease, the potential risks it poses, and general Legionella risk management and control procedures.

Legionnaires’ disease was named after an outbreak of a pneumonia-like disease that occurred in the Belle Vue Stratford hotel in Philadelphia, PA in 1976, where there was a convention of the American Legion. Legionella pneumophila, the causative organism for most cases of Legionnaires’ disease, was thought to have been present in the hotel’s cooling towers and somehow water droplets in the form of an aerosol contaminated the air conditioning system and hence they came into contact with a highly susceptible population at the convention. The disease causes pneumonia type symptoms and can leave permanent lung damage for survivors, and is fatal in 12 – 15% of cases across the population. It is interesting to note however, that recent studies show that the fatality rate increases dramatically when the disease is caught in a hospital environment. In this case, nosocomial Legionnaires’ disease has a fatality rate of approximately 30%.

Legionella Bacteria

Those Most at Risk

The most susceptible people to the organisms that cause Legionnaires’ disease are the old, people who are recovering from surgery, patients on immunosuppressive drugs, people who have lung disorders and people who smoke tobacco products. It is a high profile condition, that has occurred in many parts of the world, with serious outbreaks in the UK, Australia, Spain, France, and many other countries around the globe, but just how serious and dangerous is it? It is hoped that the following statistics can help you to decide for yourself.

There are many different estimations of just how common a disease this is and some of the following are readily available from the US Health and Safety Association, OSHA, CDC, Centre for Disease Control in Atlanta, and indeed from the PHLS in the UK.

Research

OSHA reports that in 1997, approx 5300 people died at work in the USA, and 25% of these died in automotive incidents. These results were a 45% improvement on the same measure in 1980, demonstrating how the increased awareness of health and safety practices have had an effect on saving lives at work.

CDC reports that approximately 1000 deaths are recorded annually in the USA, but suggests that this may be a fraction of the true number as most go undetected.

OSHA estimates that the number of Legionnaires’ disease cases in the USA is between 25,000 and 30,000, with approximate fatalities at 4000 per annum.

In the UK there are approximately 300 cases reported annually with approx 14% fatalities, again there is a belief that the majority of cases are undetected.

Whatever the true number, it is a sobering thought that there are more deaths attributed to Legionnaires’ disease in the USA than any other cause of death in the workplace!

In many countries there is legislation, or guidelines, that are designed to minimise the risks. In the UK the L8 document by the Health and Safety Commission provides excellent advice for water systems.

UK's Health and Safety Commission - ACoP L8

In general, the services of a good water treatment professional are essential to provide:

A Legionella risk assessment of water systems, including cooling towers, hot & cold-water distribution systems including taps, showers, spas, Jacuzzis, in fact all engineered water systems.

Provide a plan to carry out remedial works to high-risk areas, provide a program for cleaning and disinfection to water systems, and hence minimise the risk of the bacteria being transported to a susceptible person.

Recommend a maintenance schedule, to provide good water conditions, eg heat treatment, or biocide dosage, dependent on the system.

A monitoring scheme to demonstrate the effect of the maintenance program, with regular analytical evaluations and subsequent actions as required.

A record scheme to demonstrate that the required actions have been carried out and have been successful in reducing the risk of Legionellosis.

Legionnaires’ disease, how dangerous is it? We leave it for you to decide!

Mike Hunter, Feb 2002.

Additional Information & Technical Support

Accepta offer an excellent range of Legionella risk management products and services including comprehensive test kits and analysis equipment, laboratory analysis services, disinfectants and sanitisers developed specifically to assist with the effective control and pro-active management of such risks. For further information, technical support and advice on all aspects of Legionella and legislative compliance please call Accepta on +44 (0) 161 877 2334 or e-mail info@accepta.com.