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Southern public health officials issue reminder about safe handling of potting mix, compost and soil

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With the arrival of spring and better weather for gardening, Southern public health officials are reminding people about the importance of safe handling of potting mix, compost and soil to protect themselves against a potentially fatal illness, Legionnaires’ disease.

Dr Susan Jack, Medical Officer of Health Southern DHB said Legionnaires’ disease, also known as legionellosis, is a type of pneumonia caused by the legionella bacteria. Legionella bacteria commonly live in potting mix, compost and soil.

“Legionellosis is preventable and Southern DHB’s Public Health Unit is working proactively to make more people aware of the risks associated with handling potting mix, compost and soil, so fewer people will develop Legionnaires’ disease, be admitted to hospital or die.

“In 2020 there have been six cases of legionellosis including one fatality in the Southern District, which followed 20 cases of legionellosis notified in Southern and, sadly, two fatalities in 2019.”

Dr Jack said symptoms (flu-like) can appear two to ten days after exposure to legionella bacteria. Symptoms present may be a cough, shortness of breath, fever, muscle pains/aches and headaches. Nausea, vomiting and diarrhoea may also occur.

“If you experience any of these symptoms after gardening, we recommend that you talk to your doctor and inform them of your gardening activity. This will help them determine whether to test you for legionellosis. Early treatment is usually effective, however if you become very sick hospitalisation may be required.”

Risk factors for developing Legionnaires’ disease are:

  • being over 60 years old
  • being a current or former-smoker
  • or having pre-existing conditions and/or compromised immune systems.

Before handling potting mix/compost/soil we recommend you:

  • Wear a face mask (N95 or P2 – masks with a dust filter/respirator) and gloves. A mask will prevent you from inhaling/breathing in the harmful legionella bacteria and gloves will prevent hand-to-mouth contact
  • Cut bags away from your face with scissors. This controls the dust particles that may contain legionella bacteria
  • Open bags in a well-ventilated/open area
  • Dampen down the potting mix/compost/soil. This controls the dust particles
  • Wash your hands thoroughly after taking off your gloves and before taking off your mask.

Dr Jack said public health staff have been working with New World supermarkets in the Southern District to make the public more aware of how to garden safely.

The popular New World ‘Little Garden’ campaign often means supermarkets have gardening displays and products, including packets of potting mix. While the Little Garden kits themselves are unlikely to contain legionella bacteria (due to being dried and pressed), once plants grow, they will eventually need to be replanted in the garden – where people use potting mix/compost/soil.

“Public health staff are encouraging retailers that sell potting mix products to place our posters next to their displays/products. We will also recommend selling N95 face masks (with a dust respirator) and gloves and displaying them next to potting mix/compost products to reinforce how to prevent Legionnaires’ disease.

“The same goes for other retailers selling potting mix products, such as garden centres which we also worked with on raising awareness in 2019.  We are grateful to New World, garden centres and other retailers for working with us to help keep our Southern community safe,” Dr Jack said.

Members of the public and retailers with questions about legionellosis can contact

  • Dunedin Public Health South office on 03 476 9800
  • Invercargill Public Health South office on 03 211 8500
  • Queenstown Public Health South office on 03 450 9156