• Giardiasis is spread by poor hygiene practices. 
  • Many people infected with Giardia parasites will not have symptoms, but can still pass on the infection.
  • It is important that you contact your doctor if you think you or your child has giardiasis.

Giardiasis is a form of gastroenteritis, also known as gastro. It is caused by a parasite called Giardia duodenalis, which can live in the bowel. Giardia is found worldwide, however is more common in areas with poor sanitary conditions.

Giardiasis can affect anyone but is more common in infants, children and adults aged 20 to 40 years. It is easily spread in childcare centres where there are children who are not toilet trained. Giardia parasites are also found in wild, pet and farm animals, and in untreated water that comes directly from lakes and rivers. 

Symptoms of giardiasis

Symptoms of giardiasis usually take an average of seven to 10 days to develop, but may take three weeks or occasionally longer. Symptoms may include: 

  • acute or chronic diarrhoea
  • weight loss
  • fatigue
  • abdominal cramps
  • the excretion of large amounts of fat in faeces (steatorrhoea) due to malabsorption of fat in the digestive system.

Most people who become infected with Giardia parasites do not develop symptoms, but can still spread the infection to others.

Causes of giardiasis

People with Giardia parasites in their faeces can infect others if they do not wash their hands properly after going to the toilet. Contaminated hands can then spread the parasites to food that may be eaten by other people or to surfaces that may be touched by other people. Hands can also become contaminated when changing the nappy of an infected infant or handling infected animals. 

Giardiasis can be spread by contaminated drinking water. It can also be spread by faecal contamination of water supplies or recreational swimming areas, such as pools and spas. People who have had giardiasis should not use swimming pools until at least one week after their symptoms have ceased, but may then swim again provided they shower carefully beforehand. 

Diagnosis of giardiasis

If you think that you or your child have giardiasis, contact your doctor. Your doctor will arrange for a stool (faeces) sample to be tested. If the results show giardiasis, the doctor will provide appropriate advice and treatment. Your doctor will also notify the Department of Health and Human Services.

Preventing the spread of giardiasis

The spread of giardiasis can be reduced if you: 

  • Have the illness diagnosed and treated by your doctor.
  • Keep children home from school or child care until symptoms have stopped.
  • Stay home from work until symptoms have stopped if you are a food handler, healthcare worker or a childcare worker.
  • Wash hands thoroughly after going to the toilet, changing nappies 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.

Where to get help

  • Giardiasis, Communicable Disease Epidemiology and Surveillance, Department of Health and Human Services, Victorian Government. 

More information

Digestive system

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Small intestine

Large intestine

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This page has been produced in consultation with and approved by: Department of Health and Human Services - RHP&R - Health Protection - Communicable Disease Prevention and Control Unit

Last updated: October 2018

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