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Page last updated on 28 February 2019

Giardiasis is the illness caused by infection with the parasite Giardia. It is common throughout the world, with around one third of people in developing countries contracting the illness at some point in their lives and overall, 2% of the developed world’s adult population. It causes a gastroenteritis that is the most common cause of chronic diarrhoea in travellers.

Key disease information

What is giardia?

Giardia is a protozoan parasite – a single-celled organism that causes gastroenteritis (or gastro). It is a cause of chronic diarrhoea in travellers, and the most commonly acquired parasite infection. The parasite Giardia duodenalis lives in the bowel and can cause diarrhoea, gas, stomach cramps, nausea and vomiting – which can last for several weeks.

How is giardia spread?

Giardia is spread by ingesting the parasite from contaminated food or fluids. How does it get there I hear you ask. Well, when you are unwell, it is possible that your normal attention to personal hygiene may lapse. Because an infected person can shed billions of parasites in their faeces, it can easily spread when hands are not properly washed after going to the toilet and surfaces and items you touch become contaminated. These can make their way into the mouth of an unsuspecting traveller through food or fluids. Because the parasite can also survive in swimming pools, if an infected person swims while still contagious others that use the pool may become infected too. Even if you avoid the swimming pool or food hall, adventurous travellers can still be at risk of giardiasis. Animals can also contract giardia and contaminate lakes and other untreated water sources, so think twice before drinking from untreated lakes and streams.

Is giardia contagious?

Yes, giardia is highly contagious and spreads easily from an infected person (who shed billions of parasites in their faeces). Even those who normally follow proper hygiene or food preparation procedures might accidently contaminate their hands and other surfaces as they battle the diarrhoea giardia causes and unsuspecting fellow travellers might inadvertently infect themselves. But it’s not just people who are the problem. It can also be contracted by drinking untreated water sources where infected animals may have contaminated them, so avoid drinking from untreated water sources such as lakes and streams.

If you have giardia, one important thing you can do is avoid the temptation to use the swimming pool and spa. People who are infected should avoid entering swimming pools or spas for at least one week after their symptoms have stopped.

What are the symptoms of giardia?

The symptoms of giardia appear around one week to several weeks after infection and may include:

  • Acute or chronic diarrhoea
  • Weight loss
  • Fatigue
  • Abdominal cramps
  • ‘Floaty’ stools that contain more fat than normal and can be difficult to flush.
How can giardia be prevented?

The best ways to prevent infection are:

  • Avoid public places as much as possible while you are experiencing symptoms.
  • Wash hands thoroughly after going to the toilet or handling animals.
  • Clean bathrooms and toilets thoroughly.
  • Do not drink untreated water.
  • Do not swim in public pools until at least one week after symptoms have stopped.
  • Do not prepare or handle food that will be eaten by other people.
  • Do not share any towel or face washer with a person who has giardiasis.

 For further information regarding giardia and its prevention, speak with your healthcare professional.

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Sources & Citations

  1. Centers for Disease Control and Prevention. Sources of infection and risk factors. Giardia Available at: (accessed 25 October 2018).
  2. Centers for Disease Control and Prevention. Giardia. Illness and symptoms. Available at: (accessed 25 October 2018).
  3. Victoria State Government. Better Health Channel. Gastroenteritis - giardiasis. Available at: (accessed 25 October 2018).

SPANZ.SAPAS.18.11.0396 - Date of preparation November 2018