• Tiny parasite that causes diarrhea

Signs and Symptoms

Symptoms may take anywhere from three to twenty-five days to show up.

  • Stomach pain, vomiting, severe gas, diarrhea
  • Nausea, chills
  • Headache, tiredness


  • Person-to-person transmission from feces of infected individual (common in institutions and day cares)
  • Drinking contaminated water (including while swimming)
  • Swallowing giardia from contaminated surfaces
  • Travelling to countries where giardia is common


  • Doctor may prescribe antibiotics
  • Some people clear infection on their own

An individual with giardia should stay home from school/daycare/work until 24 hours symptom free.


  • Long-term intestinal symptoms (chronic diarrhea, cramps, bloating)


  • Thorough hand-washing before handling food, before eating, and after toilet use
  • Boiling water for one full minute when camping, canoeing, hiking
  • Being cautious when travelling outside of Canada (avoid drinking unclean water or eating food that has been washed in unclean water)

Giardiasis is a reportable disease and must be reported to your local Medical Officer of Health under the Health Protection and Promotion Act.