3 min read

Legionnaire’s Disease: What Is It?

Disclaimer: This information is not a substitute for professional medical advice, diagnosis or treatment.

Legionnaire’s disease (also known as Legionellosis) is a form of pneumonia caused by bacteria that thrives in wet, damp environments. It primarily affects the lungs and can lead to serious respiratory symptoms.

You can be exposed to the bacteria by breathing in tiny droplets of contaminated water or mist, often found in areas like soil, potting mix, spa baths and air conditioning systems^₁.

How common is it?

Each year, roughly 400 people in Australia contract Legionnaire’s disease. In Sydney alone, there were two Legionnaire’s outbreaks in 2025, impacting 17 individuals. Sadly, one person passed away after being exposed to the bacteria in the city’s CBD.

What are the symptoms?

Legionnaire’s disease doesn’t show up immediately, symptoms can appear up to 10 days after exposure and often resemble the flu:

Fever and chills
A cough (dry or with mucus)
Shortness of breath or difficulty breathing
Muscle aches and headaches
Loss of appetite
In rare circumstances gastronomical symptoms such as diarrhoea or vomiting

A urine or sputum test as well as a chest X-ray can help doctors confirm if you have Legionnaire’s disease^₄.

How do you contract Legionnaires disease?

Legionnaire’s disease isn’t passed from person to person, instead it spreads through inhaling contaminated water droplets or dust in the environment.

In Australia, the main sources of infection are:

Legionella pneumophila: found in places likes air conditioning cooling towers, whirlpool spas, showerheads, and other damp spots.
Legionella longbeachae: typically found in soil and potting mix

How to protect yourself:

Here are some simple tips to help avoid Legionnaires’ disease:

Check your air conditioning units: Clean your home unit regularly. If you live in an apartment or larger building, check that your building manager is on top of cleaning, disinfecting, and maintaining cooling systems.
Handle potting mix safely: Always wet potting mix before use, wear gloves and a mask (P2 or N95 is best) and wash your hands thoroughly once done in the garden.

How Legionnaire’s disease is treated:

To treat Legionnaire’s disease, you will typically be given a course of antibiotics. Most people recover with the appropriate medical care, though hospitalisation may be required in more serious cases. Early diagnosis and treatment are key to reducing the risk of complications.

Are you worried about Legionnaires’ disease or experiencing any of the mentioned symptoms? Don’t wait – book an appointment or join the queue to speak with an experienced and Australian-registered doctor at a time that suits you.