Young, fit and healthy people are less commonly affected. The disease does not spread from person to person.
Gardeners and farmers can take simple steps to reduce the risk of getting Legionnaires' disease, says Dr Neil de Wet, Medical Officer of Health.
"When working with compost and potting mix it's important to take measures to avoid inhaling dust. For example, open potting mix and compost bags gently and away from your face, cut the bag open with scissors rather than ripping it, water gardens gently using low pressure, and avoid working in unventilated places such as closed sheds and greenhouses," he says.
"When potting plants, gently wet the soil or compost first to reduce dust, and wash your hands after handling soil or compost. Use of a face mask is recommended especially when these other measures are not practical or possible."
For more information go to www.ttophs.govt.nz/legionellosis