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Giardiasis

Topic Overview

Picture of the lower digestive system

What is giardiasis?

Giardiasis (say "jee-ar-DYE-uh-sus") is an infection of the intestines caused by the parasite Giardia lamblia.

The illness, also called giardia (say "jee-AR-dee-uh"), is most often a problem in undeveloped countries where tap water is not safe.

How can you become infected with giardia?

You may 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.

You can get giardia from someone else through:

  • Close contact with someone who is infected.
  • 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 contact.

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 symptoms.

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 symptoms.

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. Taking all the medicine is important 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, doctors 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 quickly.

Some people with giardiasis have temporary trouble digesting milk and milk products. This is called lactase deficiency. 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.

Other Places To Get Help

Organizations

Centers for Disease Control and Prevention (CDC)
1600 Clifton Road
Atlanta, GA 30333
TDD: 1-888-232-6348
Email: healthyswimming@cdc.gov
Web Address: www.cdc.gov/healthyswimming
 

The CDC Healthy Swimming website provides tips and fact sheets to help people reduce the chances of getting an illness from swimming in recreational waters such as lakes, rivers, swimming pools, and oceans. CDC's Healthy Swimming program also provides resources to raise awareness about recreational water illnesses (RWIs) and how to prevent them by practicing "Healthy Swimming" behaviors.


Centers for Disease Control and Prevention (CDC): Parasites
1600 Clifton Road
Atlanta, GA  30333
Phone: 1-800-CDC-INFO (1-800-232-4636)
TDD: 1-888-232-6348
Email: cdcinfo@cdc.gov
Web Address: www.cdc.gov/parasites
 

The U.S. Centers for Disease Control and Prevention (CDC)'s website on parasites offers information on diseases caused by parasites. It provides information on topics such as malaria, neglected tropical diseases, and parasitic infections in the United States. There are also links to related information, such as a glossary and a site on healthy water, and other references and resources, such as statistics on parasitic diseases.


Centers for Disease Control and Prevention: Travelers' Health
1600 Clifton Road
Atlanta, GA  30333
Phone: 1-800-CDC-INFO (1-800-232-4636)
TDD: 1-888-232-6348
Email: cdcinfo@cdc.gov
Web Address: wwwn.cdc.gov/travel
 

The CDC's Travelers' Health Web site provides health information for the traveler. The Web site provides information on immunizations that are needed for travel to various areas of the world. It also provides information for safe travel, including traveling with children and with people who have special needs. Information about current outbreaks of disease in the world is also provided. The CDC is the leading federal agency for protecting U.S. citizens' health and safety by providing credible health information and health promotion.


KidsHealth for Parents, Children, and Teens
Nemours Home Office
10140 Centurion Parkway
Jacksonville, FL 32256
Phone: (904) 697-4100
Web Address: www.kidshealth.org
 

This website is sponsored by the Nemours Foundation. It has a wide range of information about children's health—from allergies and diseases to normal growth and development (birth to adolescence). This website offers separate areas for kids, teens, and parents, each providing age-appropriate information that the child or parent can understand. You can sign up to get weekly emails about your area of interest.


References

Other Works Consulted

  • Adachi JA, et al. (2007). Infectious diarrhea from wilderness and foreign travel. In PS Auerbach, ed., Wilderness Medicine, 5th ed., pp. 1418–1444. Philadelphia: Mosby Elsevier.
  • American Academy of Pediatrics (2009). Giardia intestinalis infections (giardiasis). In LK Pickering et al., eds., Red Book: 2009 Report of the Committee on Infectious Diseases, 28th ed., pp. 303–305. 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.
  • Yoder JS, et al. (2010). Giardiasis surveillance—United States, 2006–2008. MMWR, 59(SS-6): 15–25.

Credits

By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
Last Revised September 9, 2011

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