Legionnaires: how infection is acquired
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Legionnaires disease is a bacterial infection that causes severe pneumonia, which can be fatal. The disease takes its name from the first recorded outbreak in 1976 at a conference of American Legionnaires (or ex-servicemen).
In that outbreak, 221 people were infected and 34 died. A bacterium that had not been identified up to then was found to be the cause and was named Legionella Pneumophilia. In recent years, there have been sporadic outbreaks in Ireland in hotels and hospitals.
Legionella bacteria thrive in warm water and are typically found in piped water or storage tanks in large buildings, air-conditioning systems and warm-water whirlpool baths or spas.
Infection is normally acquired by breathing in water droplets from these sources. After an incubation period of between two and 10 days, symptoms of pneumonia occur.
These include coughing and fever. As the infection develops, a person may experience sharp pain at the side of the chest while breathing, as the lining of the lung becomes infected.
The presence of Legionella can be confirmed by urine tests, or tests on the sputum.
In previously healthy people, legionnaires disease causes death in about one in 10 cases, or higher if there is pre-existing lung disease or if the patient has a weakened immune system.
- Edel Kennedy
