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 and laboratories 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 35 Giardia cases are notified to the Public Health Service each year. 


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

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

How is it spread?

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


Hand washing

Wash your hands thoroughly:

  • after going to the toilet or changing nappies
  • before preparing or handling food
  • after touching animals
  • after gardening.

General Cleaning

Clean surfaces that may have become contaminated, especially bathrooms and toys that unwell children may have handled.

Safe Drinking Water

Avoid drinking untreated water. Untreated water 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.


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


Unwell children should not share bathwater with well children.

Attendance at work, school or preschool

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