Giardiasis (gee-ar-dye-a-sis) is an infection of the digestive system caused by tiny parasites called Giardia intestinalis (also known as Giardia lamblia, or Giardia duodenalis).
Diarrhoea is the most common symptom of giardiasis.
Other symptoms can include:
foul-smelling flatulence and belching
nausea (feeling sick)
fatigue (extreme tiredness)
loss of appetite
weight loss caused by malnutrition
medicines called metronidazole or tinidazole are used.