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What Is Giardiasis?

Giardiasis is the most common nonbacterial cause of diarrhea in the United States. It affects approximately 20 percent of the world's population, and is most common in developing countries, where infections are associated with poor sanitary conditions.
 
Giardiasis is caused by a single-celled, microscopic parasite called Giardia intestinalis. A person may develop giardiasis if he or she accidentally swallows the parasite, which is found in:
 
  • Soil
  • Contaminated food or water
  • Surfaces that have been contaminated with feces from infected humans or animals.
 
Anyone can get giardiasis, but people who are more prone to the condition include:
 
  • People who swallow water from contaminated sources
  • Hikers who drink untreated, unfiltered water
  • Parents of infected children.
 
(Click Giardiasis for more detailed information on giardiasis and its most common symptoms, methods for diagnosis, and prevention tips.)
 
Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD