What you should know about handling soils, compost and potting mix

If you handle garden soils, compost and potting mixes, you need to be aware of the possible risk of contracting Legionellosis (also known as Legionnaires Disease or Pontiac Fever).

What is Legionellosis?

It is a chest condition with symptoms similar to pneumonia. It develops in severity from a mild flu-like illness to a more severe respiratory condition. Common early symptoms include loss of appetite, muscle pains, headache, abdominal pains and diarrhoea, with fever and a dry cough developing as the disease progresses. The incubation period for the development of pneumonia is from two to ten days.

What causes this type of illness?

Legionellosis is caused by a bacteria that occurs naturally in the environment. About thirty different strains of the Legionella bacterium are known.  It is suspected that a person contracts the illness by breathing in dust or water vapour containing the bacteria.  One strain of bacteria called Legionella pneumophilia has been responsible for illnesses linked to air conditioning systems in buildings. Another strain called Legionella longbeachae, which occurs in soils, composts and potting mixes, has recently been found to cause illness in some people.

Are some people more at risk than others?

People who are susceptible to lung diseases or chest conditions are more prone to Legionella infections. Those who are middle aged, elderly, immune-suppressed and those who smoke are most at risk. It is important for the illness to be diagnosed and treated promptly because of the possibility that complications may develop. If you come into one of these categories you should make sure you take the precautions given in this factsheet.

How is Legionellosis treated?

Usually patients are put on a course of antibiotics. The illness responds readily to treatment.

Can you become immune to Legionella?

Yes, if exposed to Legionella you can contract a mild form of the disease without realising it and your body builds up antibodies which gives immunity to future infection.  This immunity is specific to the particular strain of Legionella to which you were exposed – you could be immune to one strain of Legionella and not another.

What should I do if I think I’m affected?

You should see your medical practitioner immediately. Your doctor may arrange for you to have a blood test or sputum test. Your doctor can give you further information and advice.

How do I avoid getting Legionellosis?

To avoid the risk of contracting Legionellosis, here are the precautions you should take:

  • water gardens and composts gently, using a low-pressure hose.

  • when opening bags of composted potting mix, do so slowly, making sure the opening is directed away from your face

  • when potting plants, wet the soil to reduce dust.

  • avoid doing this work in unventilated places such as enclosed green houses

  • wash your hands thoroughly after handling soils

If these precautions aren’t practicable, you should consider wearing a disposable face mask. The mask should be P1 or P2 particulate mask as specified in the Australian/New Zealand Standard 1715:2009 – Selection, use and maintenance of respiratory protective equipment, or the Australian New Zealand Standard 1716:2003 – Respiratory protective device.

For people handling soil, potting mix and compost in the workplace advice should be sought from the Department of Labour, as this agency is responsible for health and safety in the workplace.

Sourced in part from: Legionellosis pamphlet 1994, Occupational Safety and Health Service, Department of Labour.



For a printable version of this Legionellosis information, click here.

For further information to prevent or reduce the chance of infection please contact a Health Protection Officer at Toi Te Ora – Public Health Service.