Bookmark this page

View Printer Friendly PDF Printer Friendly PDF

Facts About...


What is it?

Giardiasis is a gastrointestinal illness caused by microscopic parasites called Giardia lamblia. Giardiasis is found throughout the world. Children are infected more often than adults.

How is it spread?

After a bowel movement or changing a diaper, hands may contact the parasite on them and can then spread to others by touch or by handing food that others will eat. Recreational and drinking water that have feces in it are common sources.

What do I look for?

You may start to feel sick within 3-25 days, but usually about 7-10 days after the parasite enters your body. You may have chronic diarrhea, frequent loose, pale and greasy stool, stomach pain, bloating, weight loss and feel tired. Children may not want to eat and may have trouble absorbing vitamins which can lead to weight loss, not growing as they should and anemia. However, it is very common to have no symptoms. In homes with confirmed giardiasis, family members who do not feel well should go see their health care provider to get tested.

How is it treated?

Your health care provider may prescribe an anti-parasitic drug to treat giardiasis. If you have the illness, you should drink lots of fluids. Fluids with water, sugar and salts (such as sport drinks) can help prevent dehydration.

How can I protect myself?

  • Wash your hands well, with warm running water and soap, rubbing together for at least 15 seconds, after using the washroom, changing diapers, before eating and preparing foods.
  • Always drink water from a safe supply. Treatment of drinking water will control the spread; however, chlorine disinfection alone will not get rid of it, you may need specific filters. If you have a private well, test the water for bacteria at least 4 times per year. The Health Department will give you sample bottles and can help you understand the results.
  • If you are sick, do not use any recreational water sites (e.g., swimming pools, hot tubs, lakes and rivers) until two weeks after you feel better.
  • Make sure you use protection if you have oral-anal sex. Wash your hands right after touching the anal area.

More information can be obtained from

Durham Region Health Department 905-723-3818 or 1-888-777-9613

October 11, 2017