Cryptosporidium and Giardia - HE1212

February 2023
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Information on preventing food- and waterborne diseases.

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February 2023
February 2023
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About these diseases and how to prevent them.

What are cryptosporidium (say ‘crip-toe-spor-idium’) and giardia? (say ‘gee-ah-dee-ah’)

Cryptosporidium and giardia are parasites found in the gut of infected people and animals.

People infected with cryptosporidium or giardia usually get diarrhoea (runny poo). Some people can get very sick from cryptosporidium or giardia.

How do you get cryptosporidium or giardia?

You get infected when you swallow the parasites, for example, by drinking contaminated water or touching your mouth with contaminated hands. People or animals who have cryptosporidium or giardia pass on the parasites in their faeces (poo). The parasites can contaminate (make unsafe) soil, food or water, or surfaces such as toys, bathroom taps or doors, and nappy change tables.

The parasites can live in the environment for long periods, especially in lakes, rivers, streams and roof water. There is no way of telling by taste, sight or smell if soil, food, water or a surface has cryptosporidium or giardia parasites.

Symptoms and illness

Cryptosporidium and giardia have similar symptoms. You need to see a doctor to find out which disease you have.

You may have some or all of the following symptoms:

  • foul-smelling or watery diarrhoea
  • stomach cramps or pain
  • lack of appetite
  • weight loss
  • bloating
  • nausea and vomiting
  • slight fever
  • fatigue (feeling very tired)
  • flatulence (wind)
  • headache.

Cryptosporidium symptoms appear between 1 and 12 days (usually 7 days) after becoming infected. You may be ill for 2 weeks or more. For some people, such as the very young or very old, cryptosporidium may last a long time and be life threatening.

For several weeks after your symptoms have gone you may continue to have cryptosporidium parasites in your faeces – you can infect other people during this time.

Giardia symptoms appear between 3 and 25 days (usually 7 to 10 days) after becoming infected. You can be ill for 3–4 days, then feel better, then the symptoms may come back. If you don’t get treatment, this can continue and you can be infectious for months.

Treating cryptosporidium and giardia

If you think you have cryptosporidium or giardia, this is what you should do.

  • Go to your doctor. They may ask to test a specimen (small amount) of your faeces for cryptosporidium or giardia. Your doctor will give you advice on how to collect the specimen and what to do with it.
  • Take medicines if your doctor prescribes them.
    • There is no treatment for cryptosporidium, but there are medicines to help the symptoms.
    • There are treatments for giardia.
  • Drink plenty of water while you have diarrhoea or vomiting.
  • Go back to your doctor if you have a child that is ill and is not able to drink.
  • Stay away from school, early childhood centres or work until 48 hours (2 days) after the symptoms have gone.

Cryptosporidium and giardia are notifiable diseases – meaning that your doctor will inform the Medical Officer of Health of the Public Health Service (PHS). The PHS may contact you to find out how you were infected. This helps prevent more cases of the infection.

Preventing cryptosporidium and giardia

Here’s what you can do to avoid getting cryptosporidium and giardia – or passing them on.

Wash your hands

Wash your hands thoroughly by using plenty of soap and hot water, cleaning between fingers and under fingernails, rinsing well and drying on a clean dry towel or paper towel:

  • before and after preparing food
  • after going to the toilet or changing a baby’s nappy
  • after caring for people with cryptosporidium or giardia
  • after playing or working with animals
  • after gardening.

If you have cryptosporidium or giardia, avoid preparing food for other people. If you must do so, wash and dry your hands well first.

General cleaning

Clean areas and surfaces (including toys) that may have become contaminated with a suitable cleaning solution.

Safe drinking water

  • Avoid drinking water that has not been treated – including water from lakes, rivers or streams, or from an area where you don’t know the quality of source water. If in doubt, make the water safe by boiling it or by installing an appropriate disinfection/filtration (treatment) unit. The performance of the treatment unit should meet the standard AS/NZS4348:1995.
  • If you have to drink untreated water that is taken from a roof, river or lake (eg, in a rural area), it should be boiled for 1 minute or put through an appropriate treatment unit.

See also the Ministry of Health’s publications Water Collection Tanks and Safe Household Water (code HE10148) and the booklet Household Water Supplies


Don’t go swimming in a pool if you have diarrhoea. You need to wait at least 2 weeks after the symptoms have gone.


If you or a child are unwell then do not share bathwater, as this can easily transmit infection.

When tramping and camping

  • Use toilets if they are available.
  • If there are no toilets, bury your toilet waste and paper. Make sure you bury it at least 50 metres away from water sources, such as rivers, lakes or springs.
  • Do not wash your hands directly in a water source. Collect water in a clean container, wash your hands with soap and water and then drain used water into the ground away from the water source.

For more information, speak to your doctor or nurse, or contact the public health service (look in the phone book or search the internet for contact details). You can also call Healthline on 0800 611 116.

Code: HE1212