Legionella – what is it?
- Legionnaires’ disease was first identified following a large outbreak of pneumonia among people who attended an American Legion Convention in Philadelphia in 1976. The bacteria responsible was named Legionella pneumophila.
- It is normally contracted by inhaling legionella bacteria found in tiny droplets of water deep into the lungs. Person-to-person spread of the disease has not been documented.
- Initial symptoms of Legionnaires’ disease include high fever, chills, headache and muscle pain. Patients may develop a dry cough and most suffer difficulty with breathing. Some patients also develop diarrhoea or vomiting. Legionnaires’ disease can be treated effectively with appropriate antibiotics.
- The incubation period is between 2-10 days (usually 3-6 days). Not everyone exposed will develop symptoms of the disease and those that do not develop the ‘full blown’ disease may only present with a mild flu-like infection.
- Certain groups of people are known to be at higher risk of contracting Legionnaires’ disease; for example, men appear more susceptible than women, as do those over 45 years of age, smokers, alcoholics, diabetics and those with cancer or chronic respiratory or kidney disease. It can be fatal in approximately 10% of cases.
- Legionella pneumophila is also responsible for a short feverish form of the illness without pneumonia, known as Pontiac fever. Its incubation period is typically between 2-3 days.
- Another species, Legionella micdadei, is responsible for a similar form of the illness without pneumonia called Lochgoilhead fever after an outbreak in Lochgoilhead, Scotland. The incubation period can be up to 9 days. A high percentage of those exposed to this agent tend to be affected. However, there have been no recorded deaths associated with either Pontiac or Lochgoilhead fevers.