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:

• air conditioning cooling towers
• decorative fountains
• humidifiers
• spas
• shower heads
• other bodies of water

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:

• fever and chills
• cough
• shortness of breath
• muscle aches and headaches
• fatigue
• loss of appetite
• diarrhoea or vomiting

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

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

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.

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:

• You are a smoker.
• You have a chronic illness such as heart disease, lung disease, diabetes, kidney disease or cancer.
• You have chronic immune suppression, for example if you take steroid medicines for a health condition.
• You are aged over 50 years.

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.

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:

• following manufacturers’ warnings on potting mix labels
• wetting the potting mix to reduce dust
• wearing gloves and a mask
• washing your hands after handling potting mix or soil

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

• HealthyWA has more information about Legionnaires’ disease.
• Learn about notifiable diseases in Australia at the Australian Government Department of Health and Aged Care Nationally notifiable diseases.
• If you have questions about Legionnaires’ disease you can call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.

Do you prefer to read in languages other than English?

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