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Legionnaires' disease

6-minute read

Key facts

  • Legionnaires' disease is a type of lung infection (pneumonia) caused by legionella
  • You can catch Legionnaires’ disease by breathing in water droplets or dust contaminated with legionella bacteria; it cannot be spread from person to person.
  • Symptoms include fever, chills, shortness of breath and coughing, which can be severe.
  • Legionnaires' disease is treated with antibiotics and sometimes requires treatment in hospital.
  • It is important that you contact your doctor as soon as possible if you think that you have been exposed to legionella

What is Legionnaires' disease?

Legionnaires' disease (also called Legionellosis) is an infection in your lungs (pneumonia) caused by legionella bacteria. It is uncommon, but may be life-threatening.

There are 2 main common species of legionella bacteria found in Australia.

Legionella pneumophilia is found in warm water environments and can contaminate:

Legionella longbeachae is found in soil and contaminates potting mix.

What are the symptoms of Legionnaires' disease?

About 2 – 10 days after exposure to legionella bacteria, you may develop Legionnaires’ disease with the following ‘flu-like’ symptoms:

Legionnaires’ disease can cause severe pneumonia, but most people recover.

Some people only develop a very mild illness called Pontiac fever.

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What causes Legionnaires’ disease?

Legionnaires’ disease is caused by breathing in dust or water vapour. contaminated with legionella bacteria. You may be exposed to the bacteria at home, work or in public places.

You cannot catch Legionnaires’ disease from other people or contact with animals.

Outbreaks often have a common source of infection, for example, a single air conditioning cooling tower.

When should I see my doctor?

You should visit your doctor immediately if you suspect you have been exposed to legionella bacteria or have symptoms of Legionnaires’ disease.

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Who is at increased risk of getting Legionnaires’ disease?

You are at higher risk of getting Legionnaires’ disease after exposure to contaminated water systems if:

How is Legionnaires' disease diagnosed?

Your doctor can diagnose you with Legionnaires’ disease by testing a sample of your blood, urine or phlegm.

It can be difficult to distinguish Legionnaires’ disease from other types of pneumonia.

Legionnaires’ disease is a nationally notifiable disease. This means that your doctor must tell the Department of Health if you’re diagnosed with Legionnaires’ disease. The Department of Health needs to monitor and track all cases of Legionnaires’ disease, in order to find outbreaks and improve healthcare responses.

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How is Legionnaires' disease treated?

Legionnaires' disease is generally treated with antibiotics. If you develop severe symptoms, you may need to be hospitalised.

Can I prevent Legionnaires' disease?

You can reduce your chance of catching Legionnaires’ disease by managing environments where Legionella bacteria usually grow.

You can prevent legionella pneumophila by making sure there are regular inspections, disinfection and maintenance of cooling towers and plumbing systems.

You can prevent contamination with legionella longbeachae that may be in soil and potting mix by:

Quit smoking to help reduce your risk, as smoking increases the risk of infection for people exposed to airborne legionella bacteria.

There is no vaccine available against Legionnaires’ disease.

Complications of Legionnaires’ disease

Legionnaires’ can cause severe pneumonia that may need treatment in hospital or an intensive care unit (ICU).

In rare cases, Legionnaires’ disease is fatal.

Resources and support

Do you prefer to read in languages other than English?

NSW Health has Legionnaires’ disease fact sheets in various community languages.

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