What is giardia?
Giardia is an infection of the bowel and gut, particularly the small intestine. It is also known as giardiasis. It is one of the most common diseases worldwide that’s carried by water.
What causes giardia?
Giardia is caused when someone is infected with the parasite Giardia duodenalis, also known as Giardia lamblia or Giardia intestinalis.
You can catch the parasite if you come into contact with contaminated:
- faeces (poo)
- people or animals.
The parasite must enter by mouth (usually by drinking contaminated water or eating contaminated food) to cause infection. Food and water can get contaminated if you do not wash your hands after going to the toilet, after changing nappies or after handling infected animals.
Some people have giardia without having any symptoms at all, but they can still spread the parasite.
Some people have gastroenteritis, with symptoms like:
- stomach cramps or bloating
- excessive gas or flatulence (wind)
- diarrhoea, which may be watery and smelly.
Some people become unable to tolerate dairy products for a few weeks.
Symptoms may last for months (especially if left untreated), and can return. If you think you might have giardia see your doctor.
People with diarrhoea, especially babies and young children, need to drink plenty of fluids to avoid dehydration.
Prescription drugs, including antibiotics, may be used to treat giardia.
To help prevent spreading giardia:
- keep infected people from going to childcare, preschool, school, the swimming pool or work until there has been no diarrhoea for 24 hours
- wash hands properly, especially after going to the toilet and before handling food
- boil water suspected of contamination before drinking.
Treating infected people reduces spread of the parasite.
Last reviewed: December 2015