Legionnaires Disease - Information Sheet

What is Legionnaires' disease?

Legionnaires' disease is a lung infection (pneumonia) caused by a bacterium named Legionella pneumophila. The name Legionella pneumophila was derived from the original outbreak at the 1976 American Legion Convention in Philadelphia. Pneumophila means lung-loving in Greek.

The bacterium has over 39 known species and 60 serogroups and numerous subtypes. It is a natural inhabitant of water and can be detected in rivers, lakes and streams. Some of the species are also found in soils.

Legionellosis occurs as two illness; Pontiac fever, the milder form with flu like symptoms that do not require hospitalization and is most cases is not diagnosed as legionella. Legionnaire's disease however is a multi symptom disease with pneumonia that can be fatal.

Guideline for personnel working near or in cooling towers

How is it contracted and detected?

The two common accepted methods of transmission are inhalation of aerosolized particles or aspiration (choking or coughing). Aspiration means choking such that secretions in the mouth get past the choking reflexes and instead of going into the esophagus and stomach, mistakenly, enter the lung.

The protective mechanisms to prevent aspiration is defective in patients who smoke or have lung disease. Aspiration now appears to be the most common mode of transmission. It should be noted that persons who smoke or are currently suffering from a lung infection are more prone to aspiration.

The incubation period of Legionnaires' disease is from two to ten days; this is the time it takes before symptoms of the illness appear after being exposed to the bacteria. For several days, the patient may feel tired and weak. Most patients who are admitted to the hospital develop high fever often greater than 39.5°C (103°F). Cough can be the first sign of a lung infection. The cough may be sufficiently severe to cause sputum production (coughed up mucous). Gastrointestinal stomach symptoms are common with diarrhea being the most distinctive symptom. Many patients have nausea, vomiting, and stomach discomfort. Other common symptoms include headaches, muscle aches, chest pain, and shortness of breath. Diagnosis is tricky as the disease first resembles a bad cold. Specialized laboratory tests are required where the sputum is placed on culture media and the bacteria grown is identified and typed before treatment can begin. Therefore it is important for workers at risk to be aware of the symptoms and the control measures available.

What are the sources for Legionnaire's Disease?

The major source is water distribution through large buildings. First the water must be contaminated with the bacterium, and as was stated earlier there are many sources. Then conditions must allow for growth; legionella grow within amoebae and other protozoa.
Water systems with stagnation (i.e. deadlegs, closed sections), scale, sediment and biofilm and temperatures between 20 and 45o C are ripe breeding grounds. Implicated sources are plumbing systems (tanks, showers, faucets), cooling towers, respiratory care equipment, humidifiers, whirlpool spas, decorative fountains, food mist machines, injection molding and even potting soil to name a few.

Recent Outbreaks

Spain, 7 Cases, October 2002On 17 October 2002, Reuters reported that Spanish health authorities were investigating an outbreak of Legionnaires' disease that killed one man and hospitalized six others.
Melbourne, 3 Cases, Oct. 2002 Three men, aged 54, 61 and 81, were hospitalized with Legionnaires' disease in Melbourne. Legal action is being considered against the owner of an industrial site with an unregistered tower. Victorian law requires registration of every cooling tower. Source: Melbourne Herald Sun
5 Travel-Related Cases, 1 Death, Sept. 2002 Legionnaires' disease was confirmed in five British people who all stayed at the same hotel in Belgium within the ten days preceding illness. Belgium health inspectors have investigated the hotel, collected water samples, and implemented control measures. The hotel remains open. Source: Eurosurveillance Weekly, 3 October 2002. Reported by Carol Joseph, EWGLI surveillance scheme project coordinator, Public Health Laboratory Service Communicable Disease Surveillance Centre, London, England
Melbourne, 2 Deaths, Sept. 2002 Two men, ages 51 and 83, contracted Legionnaires' disease in Melbourne and have died Health officials are investigating. Source: The Age
Stavanger, Norway, 3 Cases, Sept. 2002 On 5-6 September 2002, Legionella infection was confirmed in a 49-year-old Sandnes man and a 55-year-old Stavanger man.. News of the three cases worried Stavanger residents because an outbreak involving 28 cases and 7 deaths occurred there during the summer of 2001. Source: Aftenposten
Essex (UK), 2 Cases, Sept. 2002 As of 25 September 2002, two men with Legionnaires' disease were in critical condition in an Essex (UK) hospital. Laboratory tests confirmed the presence of Legionella. The Essex Health Authority is investigating both cases to identify potential links

Can the risk of Legionnaires' Disease be determined by geographical location?

No. Legionnaires' disease is not specific only to certain areas. Although some areas have reported more cases of LD than other areas, the geographic location is relatively insignificant. What's more, the number of cases reported from a given area could indicate the level of awareness among physicians and the availability of laboratory testing, as opposed to the level of legionellae in the water supply. Legionella contamination is usually tied to the condition of a building's mechanical system, which is independent of geographical location.

Waterloo, Canada, 3 Cases Sept. 2002 On 10 September 2002, it was reported that two construction workers, ages 34 and 47, were in critical condition after contracting Legionnaires' disease a week prior. Both had been doing renovations to the roof of a hospital in the Waterloo area. A 44-year-old female patient at the same hospital was diagnosed with the disease on 7 September. Source: The Record

Protection

The best protection is to reduce the risk as much as possible. Risk reduction strategies include

controlling the source of contamination -this is using measures to eliminate growth in water systems. Control measures include ensuring a clean supplied of makeup water, minimizing growth conditions by using measures such as water treatment to control biofilm growth, eliminating sediment and scaling in systems, and killing bacteria. Eliminating areas of stagnation in the system by design changes or scheduled maintenance and cleaning of systems.
preventing transmission -measures include physical controls such as grates or barriers in cooling towers to respiratory protection for workers
maintain awareness - workers in the higher risk areas should be aware of the signs and symptoms of the disease. Sick leave should be monitored on these workers particularly for possible pneumonia like symptoms

Final Notes

With a good maintenance system and control measure such as use of biocide or chlorination of cooling waters the risk for workers is minimal. Personal protection for cooling tower workers of respirator and goggles will also further reduce the risk, not only to legionella but also from the control measures used in the cooling waters (biocides and chlorine). Finally awareness, monitor your health, if you smoke try to quit (smokers are at higher risk of contacting legionnella) and ask questions if you are unsure. At the University of Ottawa use safety@uottawa.ca.

acknowledgments to

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