Home > Patients & Visitors > Health Library > Giardiasis
"jee-ar-DYE-uh-sus") is an infection of the intestines caused by the parasiteGiardia lamblia.
The illness, also called
giardia (say "jee-AR-dee-uh"), is most often a problem in undeveloped countries where tap water is
become infected with giardia if you eat food or drink water that is tainted
with human or animal waste. In the United States and Canada, you can get
giardia by drinking untreated water from wells, streams, rivers, and lakes.
This is true even in mountain lakes and streams where the water may seem very
pure. The infection can also happen if you swallow contaminated water while you swim.
You can get giardia from someone else through:
Giardia can cause diarrhea,
stomach cramps, gas, and nausea. You may feel sick once and then get better. Or
your symptoms may come and go for some time. Some children with giardiasis do
not grow or gain weight normally. Sometimes giardiasis does not cause any
After a person is exposed to the parasite, it usually
takes 7 to 10 days for the infection to develop, but it can take from 3 to 25
days or longer. You can pass the infection to others during the entire time you
are infected. You may be infected for months, even if you don't have
Your doctor will ask questions about your past health and will do a physical exam to find out if you have giardiasis. He or she may also test your stool for the parasite that causes the infection.
Your doctor may prescribe
medicine to kill the parasite. Treatment also lowers the chance that you will
pass giardia to others. It's important to take the medicine for as long as prescribed, so the infection
does not come back.
In some situations, you may be tested for giardiasis even though
you don't have any symptoms. For example, this could happen during an outbreak
at a day care center. If tests show that you are infected, your doctor may recommend that
you get treatment even if you don't have symptoms. This is because a small
number of people who are not treated get a long-term infection.
If you have diarrhea, try eating small amounts of bland food until you
feel better. This gives your bowel a rest. But you need to take frequent sips
of clear fluids like rehydration drinks to avoid dehydration. This is
especially important for children, because they can become dehydrated
Some people with giardiasis have temporary trouble digesting milk and milk products. This is called lactose intolerance. If you have this problem, avoid these foods for at least 1 month. Then slowly add them back into your daily meals as your body can handle them.
There are some things
you can do to avoid giardiasis.
Learning about giardiasis:
Other Works Consulted
Adachi JA, et al. (2012). Infectious diarrhea from wilderness and foreign travel. In PS Auerbach, ed., Wilderness Medicine, 6th ed., pp. 1360–1374. Philadelphia: Mosby.
American Academy of Pediatrics (2015). Giardia intestinalis (formerly giardia lamblia and giardia duodenalis) infections. In DW Kimberlin et al., eds., Red Book: 2015 Report of the Committee on Infectious Diseases, 30th ed., pp. 353–355. Elk Grove Village, IL: American Academy of Pediatrics.
Huston CD (2010). Intestinal protozoa. In M Feldman et al., eds., Sleisenger and Fordtran's Gastrointestinal and Liver Disease, 9th ed., vol. 2, pp. 1905–1919. Philadelphia: Saunders.
Roy SL, Hlavsa MC (2012). Giardiasis. In GW Brunette et al., eds., CDC Health Information for International Travel 2012: The Yellow Book. New York: Oxford University Press. Also available online: http://wwwnc.cdc.gov/travel/yellowbook/2012/chapter-3-infectious-diseases-related-to-travel/giardiasis.htm.
Yoder JS, et al. (2010). Giardiasis surveillance—United States, 2006–2008. MMWR, 59(SS-6): 15–25.
ByHealthwise StaffPrimary Medical ReviewerE. Gregory Thompson, MD - Internal MedicineAdam Husney, MD - Family MedicineSpecialist Medical ReviewerW. David Colby IV, MSc, MD, FRCPC - Infectious Disease
Current as ofMay 24, 2016
Current as of:
May 24, 2016
E. Gregory Thompson, MD - Internal Medicine & Adam Husney, MD - Family Medicine & W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
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