Giardia is a parasite (living thing) found in the guts of people and animals such as cattle, sheep, cats and dogs. It is also found in infected water such as lakes and streams. You can get giardia (or giardiasis) if you swallow contaminated water. Giardia can cause vomiting and diarrhoea (gastroenteritis).

Symptoms of giardia

Symptoms usually start 7 to 10 days after being infected. They usually last between 3 and 4 days.

The symptoms include:

  • diarrhoea
  • stomach pain or cramp
  • feeling sick and throwing up (vomiting)
  • a slight fever.

Many people do not get any symptoms.

Diagnosing giardia

Giardia is diagnosed from a poo (faeces) sample.

If the tests find the giardia infection, your healthcare provider will report this to the local public health team. They may contact you for more information. This is to help stop the infection spreading further.

Treating giardia

Giardia is treated by a course of antibiotics. You should also rest and drink plenty of fluids to prevent dehydration. See the self care section on the gastroenteritis page for more details.

Gastroenteritis (internal link)

Getting help with giardia

You should see your healthcare provider if:

  • you have bloody diarrhoea
  • you have a fever
  • your symptoms have not gone away after 7 days.

You should also see your healthcare provider if you are very unwell or if you have a weakened immune system.

You should take your tamaiti (child) to your healthcare provider if they:

  • are not drinking
  • are passing less wee (urine) than usual
  • have a dry mouth or sunken eyes
  • seem drowsy.

Avoiding spreading giardia

To reduce the risk of spreading the infection, it is important to have good hand hygiene. This includes washing your hands with soap and water, especially after using the toilet.

Keep your hands clean: Healthy habits (internal link)

Try to avoid preparing food if you have giardia. If you do prepare food, make sure you wash and dry your hands well first. Follow food safety advice.

Preparing and storing food safely at home — New Zealand Food Safety (external link)

Stay away from work, community gatherings and school or preschool until you or your tamaiti (child) have been free of symptoms for 48 hours. This includes the last time you had diarrhoea.

You should wait for at least 2 weeks after the last episode of diarrhoea before you go swimming in a pool.

Clinical review

This content was written by HealthInfo clinical advisers. It has been adapted for Health Information and Services.

Clinical advisers — HealthInfo (external link)