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HealthInfo Waitaha Canterbury

Legionnaires' disease (legionellosis)

Legionnaires' disease is a chest infection (pneumonia) caused by the Legionella bacteria. People usually catch the disease by breathing in water droplets that contain the bacteria.

The most common source of these water droplets is potting mix or compost. Other sources are piped hot water, air conditioners and spa pools.

Anyone can get Legionnaires' disease. But if you're over 50, smoke, have a long-term illness (especially lung disease) or have low immunity, you may be more likely to catch it, and the effects may be more serious for you.

Symptoms of Legionnaires' disease

Symptoms include:

If you have any of these symptoms and have recently been handling potting mix or compost, see your GP as soon as possible. Make sure you tell your doctor that you've been in contact with these products.

Legionnaires' disease is diagnosed from a sputum (mucus or phlegm) sample. You may also have a blood test and a chest X-ray.

Treating Legionnaires' disease

Legionnaires' disease is treated with antibiotics.

Preventing Legionnaires' disease

To avoid getting Legionnaires' disease, be very careful when using potting mix, seed raising mix, compost or other soil products. It's very important that you do not inhale the dust from any of these products.

To keep yourself safe, follow these guidelines:

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Written by HealthInfo clinical advisers. Last reviewed June 2021.


Page reference: 49708

Review key: HILEG-49708