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What is Giardia?

Giardia is a parasite that causes an infection in the intestinal track. Symptoms usually start 3 to 25 days after being exposed to the parasite.

What are the symptoms?

  • Asymptomatic (no symptoms)
  • Diarrhea
  • Abdominal cramps
  • Bloating
  • Flatulence (passing gas)
  • Frequent loose, pale, greasy stools
  • Fatigue (tiredness)
  • Weight loss

How is it spread?

  • Person-to-person by way of fecal-oral route (e.g., hand to mouth contamination).
  • Person-to-person by way of sexual acts (e.g., anal intercourse).
  • Drinking or eating contaminated water or food.

Is there a treatment?

Drink plenty of fluids. Keep yourself hydrated if you are experiencing diarrhea. Antibiotic treatment with either Metronidazole or Tinidazole is usually needed to kill this parasite. Follow-up with your health care provider if symptoms persist, worsen, or reappear. Continued infection can lead to long-term complications, such as arthritis or damage to the

lining of the intestines.

Can it spread from person-to-person?

The giardia parasites are released with the bowel movements of infected humans or animals. It is spread from one person to another through the fecal-oral route. For example, touching your mouth with contaminated hands, or putting something in your mouth that has come in contact with the germ can spread the infection. Even persons infected with giardia that have no symptoms can pass on the disease to others.

How do I prevent infection?

  • Proper handwashing with warm water and soap is the best way to prevent infections. Always wash hands:
  • Before and after preparing food.
  • Before eating.
  • After changing or handling diapers.
  • After using the toilet.
  • After working in the garden.
  • After contact with animals or their feces.

Water safety:

  • Drink water from a safe water supply, especially when travelling.
  • Chemical purifiers alone won’t kill this parasite. When travelling, camping, or using well water, be aware of methods such as boiling (for at least five minutes) to make water safer to use.
  • When travelling, use bottled water. Make sure the seal hasn’t been tampered with before drinking and brushing teeth. Avoid consuming ice cubes, salads, and other foods like raw  vegetables and fruit that may have been washed with contaminated water.
  • Don’t swallow water from open lakes, streams, or outside taps.

When ill with diarrhea:

  • Avoid recreational water venues (e.g., swimming pools, wading pools, and splash pads) for at least two weeks after symptoms have passed.
  • Don’t prepare or handle food or drinks for others.
  • Food handlers, health care and daycare workers, and people who attend daycare settings should stay home from work until 24 hours after diarrhea has stopped to help reduce thechances of spreading the parasite.

Cases are reportable to the Health Unit immediately, except asymptomatic cases.  

For more information on laboratory diagnosis, refer to the Ontario Public Health Lab