Summary
Read the full fact sheet- Legionnaires’ disease is a form of pneumonia (lung infection).
- Symptoms include cough, shortness of breath, fever and headache.
- People who smoke and people with underlying medical conditions are at higher risk of getting very sick if they get Legionnaires’ disease.
- Legionella, the bacteria that causes Legionnaires’ disease, is common in the environment, especially in fresh water and soil. There are easy steps that everyone can take to prevent infection.
- Legionnaires’ disease can be treated with antibiotics and early treatment can reduce severity.
On this page
About Legionnaires’ disease
Legionnaires’ disease is a type of pneumonia (lung infection) caused by Legionella bacteria, which are widespread in our environment.
Legionella is found in natural water bodies such as rivers, lakes, creeks and hot springs. The bacteria are also found in spas, potting mix, warm water systems and artificial systems that use water for cooling, heating or industrial processes, such as cooling towers.
A person may catch Legionnaires' disease by breathing in fine droplets of water that contain the bacteria. Legionnaires' disease cannot be caught from another person or by drinking contaminated water.
Risks of Legionella infection
Although Legionella is common in the environment, not everyone who breathes in the bacteria will become unwell. People at greater risk of getting Legionnaires' disease include those who:
- are older (usually over 65)
- smoke
- drink heavily
- have a chronic lung disease like emphysema
- have underlying medical conditions such as diabetes, cancer or kidney failure
- have another illness or are taking medication that weakens the immune system.
Symptoms of Legionnaires' disease
The symptoms of Legionnaires' disease usually begin to appear within 2 to 10 days of breathing in the bacteria. Common symptoms include:
Diagnosis and treatment for Legionnaires' disease
Pneumonia is usually diagnosed using a chest x-ray. Most people with pneumonia will have a cause other than Legionella, and special tests are needed to diagnose Legionnaires’ disease. These may include:
- a urine test
- tests on sputum (mucus that is coughed up) or other samples from the lung
- blood tests taken during the illness and after recovery.
The infection can be treated with appropriate antibiotics.
Most people with Legionnaires’ disease will be admitted to hospital.
There is no vaccine to prevent the disease.
Prevention of Legionnaires' disease
The risk of Legionnaires’ disease can be reduced by ensuring the growth of Legionella bacteria in systems such as spas, hot water systems and cooling towers is controlled.
People can also take care to avoid exposure to the bacteria from other sources, such as potting mix and water sources in the home.
Maintenance and treatment of artificial systems
Government regulations set out how to maintain and treat cooling towers, water delivery systems in hospital and aged care facilities and public spas to prevent the Legionella bacteria growing. For further information, visit Legionella risk management page.
Hot water systems
Hot water systems can harbour Legionella in places where there may be stagnant or warm water (25 to 50 °C). Examples include shower nozzles, hot water taps, hot water storage vessels, combination hot/cold water delivery units and hoses or filters attached to shower roses or tap outlets.
Domestic plumbing systems must be properly installed and maintained to avoid growth of Legionella. Consult a plumber if you have any concerns.
Spa pools
Spa pools require careful maintenance, disinfection and frequent cleaning because they provide ideal conditions for the growth of Legionella, which can be carried into the lungs by aerosols (tiny air particles) created by the spa pool jets.
The correct use of spa pool water chemicals, good management of the disinfection, filtration and recirculation systems and regular cleaning of spa pool surfaces can keep spa pool water in a clean, safe and healthy condition.
Fountains
Fountains can create aerosols by splashing water, and are a particular risk if the water is warm or heated intermittently by submerged lighting. Regular draining, cleaning and disinfection is recommended.
Nebulisers and humidifiers
Nebulisers need regular cleaning in accordance with manufacturer instructions.
Nebuliser pumps should have regular service and filter changes, in accordance with the manufacturer’s instructions.
When using a humidification device, use only distilled water or water that has been boiled and allowed to cool. After using a humidifier, empty it and clean it in warm water and dishwashing liquid, then rinse and allow all components to air dry.
Spa baths
Drain spa baths after each use, and make sure they are inspected frequently, and cleaned and maintained regularly to ensure hygienic operation. Keep the entire system dry when not in use.
Domestic evaporative air conditioners
Correct maintenance of evaporative air conditioners is essential to control the accumulation of sediment, bacteria, mould and algal growth inside the unit.
Always use and maintain evaporative cooling systems in accordance with manufacturer’s guidelines.
Portable evaporative cooling units
Portable evaporative cooling units need to be completely drained at least once a week during the summer season.
When units are not being used for an extended period they need to be completely drained, cleaned, and left to dry.
Take care with potting mix
Cases of Legionnaires' disease have been linked to the use of potting mix. To minimise the risk of contracting Legionnaires’ disease from soil, compost or potting mix, take the following precautions:
- Wear a mask and gloves when handling soil, compost or potting mix.
- Wash hands carefully with soap and water after handling soil and before eating, drinking, smoking or placing hands near the face or mouth.
- Store bags of potting mix in a cool dry place. When stored in the sunlight, the temperature inside the bag can increase, creating an ideal environment for Legionella bacteria to grow.
- Open bags in a well-ventilated space.
- Open bags of composted potting mix slowly, directing the opening away from the face to avoid inhaling the mix. Wet the soil to reduce dust when potting plants.
- Water gardens and composts gently, using a low-pressure hose.
- Avoid breathing in droplets of water from dripping pot plants, including hanging baskets, and when watering plants.
Where to get help
- Your GP (doctor)
- Your local hospital
- Your local council
- Communicable Disease Section, Department of Health, Victorian Government Tel. 1300 651 160
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