Legionnaires' Disease

Legionnaires' disease, or Legionellosis, is a type of pneumonia usually caused by the bacterium Legionella pneumophila.

• Legionnaires' disease, or Legionellosis, is a type of pneumonia usually caused by the bacterium Legionella pneumophila.
• Legionella got its name in 1976, after an outbreak of the disease among people attending a convention of the American Legion.
• Symptoms usually begin 2 to 14 days after exposure, and may include high fever, chills and cough, and sometimes also muscle aches and headaches.
• Legionnaires' disease is usually successfully treated with antibiotics, although it may prove fatal in some cases.
• Legionella can also cause Pontiac fever, a milder form of the disease.

What is Legionnaires' disease?

Legionnaires' disease is a form of pneumonia caused by the bacteria belonging to the family Legionellaceae. Most cases of Legionnaires' disease are caused by the bacterium Legionella pneumophila. The bacterium got its name in 1976, after an outbreak of the disease among people attending a convention of the American Legion, in Philadelphia.

The source of the bacterium was found to be contaminated water used to cool the air in the hotel's air-conditioning system.

How do you get Legionnaires' disease?

Legionella bacteria occur naturally in the environment, usually in water, and particularly in warm water. Legionnaires' disease sources may include almost any warm water system, especially those that produce aerosols, sprays or mists. Examples of suspected sources in cases of Legionella include whirlpool spas, mist machines, humidifiers, hot tubs, hot springs, cooling towers, hot water tanks, large plumbing systems and parts of the air-conditioning systems of large buildings.

Car and window air conditioners do not seem to be favourable environments for growth of the bacteria.

People get Legionnaires' disease when they breathe in small airborne water droplets that are contaminated with the bacteria. There is no evidence that the bacteria can spread from one person to another.

Outbreaks of Legionnaires' disease have occurred in hospitals: hospital buildings have complex water systems, and many hospital patients already have illnesses that increase their risk for Legionella infection. Other outbreaks have been linked to cruise ships and hotels.

Who is at risk?

People at highest risk of getting ill from Legionella are the elderly, smokers, those with chronic lung disease, and those with weakened immune systems from diseases like HIV/Aids, cancer, diabetes or kidney failure, or from taking drugs to suppress the immune system (e.g. after a transplant operation or chemotherapy).

What are the symptoms of Legionnaires' disease

Symptoms usually begin 2 to 14 days after being exposed to the bacteria, and may include high fever, chills, cough and fatigue. Gastrointestinal complaints, muscle aches and headaches also occur in some cases.

Symptoms of Legionnaires' disease are very similar to other types of pneumonia, so it is necessary to do clinical tests on sputum, blood or urine to definitively identify the bacterium. Chest X-rays are also taken.

Pontiac Fever

Pontiac Fever is a milder, non-pneumonia infection caused by Legionella. The symptoms, which usually last for 2 to 5 days, are flu-like and may include fever, headaches and muscle aches. The symptoms resolve without treatment, and no deaths have ever been reported.

How is Legionnaires' disease treated?

Most cases of Legionnaire's disease are treated successfully with antibiotics, and otherwise healthy people usually recover. However, the disease can be very serious and is fatal in up to 5% to 30% of cases.

What should I do if I think I've been exposed to Legionella?

Most people exposed to the bacteria do not become ill. However, if you think you might have been exposed to the bacteria, it is very important to consult your doctor without delay. You should let him or her know if you have travelled recently.

Should you prove to be infected, no special precautions as regards other people are necessary, as Legionnaires' disease is not contagious. If you or your doctor suspect a building (such as your workplace) contains the source of the infection, then the relevant health authorities should be notified.