Giardia (Beaver Fever)

What is Giardia?

Giardia (pronounced Gee-are-dee-ah) is a common parasite that causes an illness known as giardiasis. Most people know it as “Beaver Fever.” The parasite that causes “Beaver Fever” is very small and cannot be seen with the naked eye.

Where is Giardia found?

Giardia can be found in the digestive system of humans and animals (e.g., beavers, dogs, and farm animals) and outside the body (e.g., in a lake and in animal feces), where it can survive for long periods of time.

How do people become sick?

The parasite Giardia can cause people to become sick when they:

  • Drink water contaminated with animal and/or human feces.
  • Contact human and/or animal feces.


Giardiasis symptoms vary, but may include:

  • Severe diarrhea
  • Nausea
  • Vomiting
  • Headaches
  • Stomach cramps
  • Chills
  • Fatigue
  • Bloating

Giardia and Drinking Water

In Newfoundland and Labrador, most communities obtain drinking water from lakes, rivers, streams and ponds (surface water). These surface water supplies are subject to animal activity. The water supplies may become contaminated if the animals have Giardia and they deposit their droppings (feces) in the water.

Disinfection (e.g., chlorination) of drinking water may not be able to destroy Giardia. It is a hardy parasite. Illness from drinking Giardia contaminated water does occur in Newfoundland and Labrador. In fact, several communities have had to issue boil water advisories due to waterborne illness outbreaks caused by Giardia.

Is there a risk from drinking water directly from roadside springs, brooks and ponds?

Yes, people can become ill with giardiasis by drinking water from roadside springs, brooks and ponds and other surface water sources. Water from these sources may be contaminated with Giardia. Boiling water obtained from these sources will destroy disease-causing bacteria.

Do not drink water from sources with unknown water quality

Giardia From Direct Contact With Feces

Coming into contact with Giardia-contaminated feces and then touching your mouth or food, may cause you and others to become ill with giardiasis. Giardia-contaminated feces can come from an infected person or animal. Because you will likely not know if feces contain Giardia, you must minimize your contact with feces and thoroughly wash your hands afterwards.


To prevent infections from Giardia:

  • follow any boil water advisory instructions (e.g., boil all drinking water for one (1) minute)
  • don’t consume untreated water (e.g. water from springs, brooks)
  • wash your hands after using the toilet, changing diapers and before handling food. Teach children to wash their hands as well.
  • don’t contact the feces of animals, especially those of your pets.

Thorough hand washing has been shown to reduce the transmission of Giardia from person to person.

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Last updated: 2019-08-13