Giardia is a parasite which lives in the digestive tract of people and animals. The parasites can live in the environment for long periods, especially in lakes, rivers, streams and roof water. It is widespread in New Zealand.  Doctors are legally required to notify the Public Health Service of cases of Giardia disease under the Health Act 1956.

In the Nelson Marlborough district around 96 Giardia cases are notified to the Public Health Service each year. Children 1 to 4 years of age have the highest incidence rate for Giardia in New Zealand.


The disease may cause diarrhoea, abdominal cramps, bloating, excessive gas, nausea, weight loss and malabsorption. People get sick between three and 25 days (usually seven to 10 days) after being infected and the symptoms can last for three to four days. Some people may display no symptoms.

Contact your GP or Healthline (0800 611 116) for further advice

How is it spread?

Giardia disease is spread from ingestion of faecally contaminated food or drinking water, swallowing recreational water, exposure to faecally contaminated environmental surfaces and person to person spread.


Drinking water taken from the roof, rivers, lakes etc, should be boiled for one minute or an approved filter (Standard AS/NZS4348: 1995) should be used. Check with your local council to ensure your water supply is of good quality.

Wash your hands:

  • Carefully after going to the toilet or changing nappies
  • Before preparing or handling food
  • As well as utensils and chopping boards in hot, soapy water after handling uncooked food
  • After touching animals

You should not swim in a public swimming pool for two weeks after symptoms clear.

People should remain away from work, school, preschool/childcare for 48 hours after symptoms have gone.