Giardiasis is an intestinal infection that may be contracted from drinking contaminated water, or from close personal contact with infected persons. Giardiasis infects a variety of vertebrates including mammals, reptiles and birds. It is a major cause of diarrhoea in humans and has been suspected of causing diarrhoea in farm animals.


Giardia duodenalis, a flagellate protozoan.


The disease organism has a widespread distribution around the world. It probably affects more people in Queensland than any other disease that can be transmitted between animals and people.


Mammals, reptiles, birds

Affected animals

  • mammals
  • humans
  • dogs
  • birds

Clinical signs


Giardial infection has been reported in animals associated with chronic diarrhoea. Young animals are the primary source of infection, with high faecal excretion rates leading to contamination of the environment. Treatment is available and can be effective in eliminating infection.


Symptoms can include:

  • diarrhoea
  • abdominal cramps
  • nausea or vomiting
  • weight loss
  • fatigue.

Symptoms can last from 1-3 weeks.

How it is spread

Giardiasis is a well-recognised problem in certain groups, including travellers, campers and people with impaired immune states.


People are the reservoir for giardia, but dogs and a wide range of animals have been implicated as sources of infection.


The disease is commonly found in cockatiels and budgerigars.

Giardia can be found in the faeces of people and some domestic animals. As a result, it can be spread by people during food preparation, and hand-to-mouth transfer of the parasite. Some infected individuals may be unaware they are transmitting the infection because they do not have any symptoms.



A range of drug treatments are available.


  • Exercise good personal hygiene.
  • Follow safe food-handling practices.
  • Wash hands after handling animals and before eating.
  • Treat suspect water supplies (the simplest treatment method is boiling water for 2 minutes).

Water can also be disinfected with 2 drops of household bleach per litre, stirred and allowed to stand for 30 minutes prior to use.

Further information