What is giardia?
Giardia is an infection of the bowel and gut, particularly the small intestine. It is also known as giardiasis. It can cause abdominal (stomach) pain and diarrhoea. Giardia infection can cause long-lasting symptoms and serious problems, especially in children. It is one of the most common diseases worldwide that’s carried by water.
What are the symptoms of giardia?
The most common symptoms are:
- diarrhoea, which may be watery and smelly
- stomach cramps or bloating
- excessive gas or flatulence (wind)
- some have gastroenteritis
Symptoms may last for months (especially if left untreated), and may lead to long-term effects like significant weight loss and malnutrition. Some people develop irritable bowel syndrome after having giardia.
What causes giardia?
Giardia is caused by infection 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 through the mouth to cause the infection and this usually happens where someone drinks contaminated water or eats contaminated food. Some countries have poor water quality and food hygiene so you need to be cautious when visiting these countries. You should not drink untreated water from rivers or lakes anywhere.
How is giardia diagnosed?
If you think you or your child has giardia, see your doctor. They may treat you with antibiotics if they have a strong suspicion of giardiasis, or they may arrange to have a sample of your stool (poo) tested for the giardia parasite.
How is giardia treated?
People with diarrhoea, especially babies and young children, need to drink plenty of fluids to avoid dehydration.
Many people with giardia get better without treatment. Some people will need prescription drugs, including antibiotics.
How can giardia be prevented?
To help prevent the spread of giardia:
- keep infected people from going to childcare, pre-school, school or work until they have not had any diarrhoea for at least 24 hours
- do not use swimming pools for at least 2 weeks after diarrhoea has completely stopped
- wash hands properly, especially after going to the toilet and before handling food
- do not share linen, towels or eating utensils with others while there are symptoms
- boil any water before drinking if you suspect it may be contaminated
Treating infected people reduces the spread of the parasite.
Learn more here about the development and quality assurance of healthdirect content.
Last reviewed: March 2020