Causes and Symptoms of Giardiasis - Minnesota Dept. of Health

Giardiasis Fact Sheet

Minnesota Department of Health
Revised 5/2018

Download a print version of this document:
Giardiasis (Giardia) Fact Sheet (PDF)

What is Giardia?

Giardia is a parasite that causes a diarrheal illness called giardiasis. Giardia is the most frequently identified parasitic infection in Minnesota and is a common cause of waterborne illness.

How is it spread?

Giardia is passed in the stool of an infected person or animal. The parasite is protected by an outer shell that allows it to survive outside the body for long periods of time. Giardia may be found in soil, food, water, or surfaces that have been contaminated with the feces from infected humans or animals.

Giardia can be transmitted by:

  • Swallowing contaminated water while swimming or drinking.
  • Having contact with people who are sick with giardiasis, especially in child care settings.
  • Swallowing Giardia organisms picked up from contaminated surfaces, like changing tables, door handles, and toys. 
  • Eating foods contaminated with the parasite.
  • Exposure to fecal material during sexual activity.

What are the symptoms?

Symptoms of giardiasis usually include:

  • Diarrhea
  • Greasy stools that can float
  • Gas and bloating
  • Stomach cramps
  • Loss of appetite
  • Weight loss
  • Slight fever

Some people have no symptoms.

Symptoms generally begin 1 to 3 weeks after exposure.

How long does it last?

Symptoms typically last about 2 to 6 weeks in healthy persons. Giardiasis can be treated with a number of prescription drugs including metronidazole, nitazoxanide, and tinidazole. Some infections are self-limited, and treatment is not required. Diarrhea should be managed by drinking plenty of fluids to prevent dehydration.

If you or your child test positive for Giardia and have no symptoms, treatment is generally not recommended.

What can I do to minimize my risk of getting it?

  • You can reduce your risk of getting giardiasis by following these recommendations:

    • Wash your hands often and with soap and water, especially after using the bathroom and changing diapers, and before handing or eating any food.
    • Do not swallow water while swimming.
    • Do not drink untreated water from lakes, rivers, springs, ponds, and streams.
    • Use caution when traveling in countries with minimal water treatment and sanitation systems by avoiding tap water, fountain drinks, ice, and raw foods.
    • Reduce fecal-oral exposure during sexual activity and avoid sexual activity with those who have diarrhea or who recently recovered from giardiasis.

What should I do if I have symptoms?

Contact your healthcare provider if you have concerns about your health. They may ask you to submit a stool (poop) specimen to diagnosis the illness.

People who have symptoms of giardiasis can reduce their risk of spreading their illness to others by following these recommendations:

  • Wash your hands carefully and frequently with soap and water.
  • Stay out of pools, splash pads, and lakes while sick.
  • Do not bathe with others while sick.
  • Do not attend or work in child care settings or preschool until 24 hours after diarrhea stops. 
  • Wait to have sex until symptoms have stopped.

To report a suspected waterborne or foodborne illness, call the Minnesota Department of Health at 1-877-366-3455 (or 651-201-5655 from the Twin Cities) or email health.foodill@state.mn.us.

Updated Wednesday, 13-Jun-2018 07:38:34 CDT