"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
How can you become infected with giardia?
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:
Close contact with someone who is
Working in day care centers for young children. For
example, if you change a diaper and don't wash your hands afterward, anything
or anyone you touch could get infected. You could even get the illness yourself
if you touch your mouth or eat food that you've touched. Children in day care
centers are also more likely to get infected.
Working or living in
nursing homes or other care centers where people may have poor bowel control
and poor hygiene.
Some types of sexual contact, such as anal-oral
What are the symptoms?
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
How is it diagnosed?
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.
How is it treated?
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.
Can giardiasis be prevented?
There are some things
you can do to avoid giardiasis.
Don't drink untreated or unpurified water.
If you are camping or hiking, boil or purify water from lakes and streams
before you drink it.
When you travel in high-risk areas, drink
bottled water and avoid raw fruits and vegetables. Don't drink beverages
containing ice cubes.
Wash your hands often to prevent getting
giardiasis from an infected person. This is very important not only after you
change diapers, use the toilet, or help someone else use the toilet but also
before you prepare food.
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 (2012). Giardia intestinalis (formerly giardia lamblia and giardia duodenalis) infections. In LK Pickering et al., eds., Red Book: 2012 Report of the Committee on Infectious Diseases, 29th ed., pp. 333–335. 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.
How this information was developed to help you make better health decisions.