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Giardia
Giardia, a one-celled microscopic parasite, causes the diarrhea-related illness giardiasis. This organism is also known as Giardia intestinalis or Giardia lamblia. After a person becomes infected, the parasite begins to multiply within the intestines. After approximately one to two weeks, symptoms can occur, including gas, bloating, and stomach cramps. Giardia is generally treated with a common prescription medication.
Giardia is a one-celled microscopic parasite. This parasite is also known as Giardia intestinalis or Giardia lamblia. Giardia is the cause of the diarrheal illness giardiasis.
Giardia is the most common nonbacterial cause of diarrhea in the United States (see Diarrhea Causes). It is also one of the most common intestinal parasites worldwide, infecting up to 20 percent of the world's population. Giardia is most prevalent in developing countries, where infections are associated with poor sanitary conditions. Infections are more common in children than in adults. However, chronic infections are more common in adults.
Giardia is found in soil, food, water, or surfaces that have been contaminated with the feces from infected humans or animals. Giardia transmission can occur by accidentally swallowing the parasite; a person cannot become infected through contact with blood.
When a person becomes infected, the parasite begins to multiply within the intestines. After one to two weeks, symptoms of Giardia can occur.
Common symptoms include:
- Diarrhea
- Gas or flatulence
- Greasy stools that tend to float
- Bloating
- Belching
- Stomach cramps
- Vomiting
- Abdominal (stomach) pain
- Upset stomach or nausea.
These symptoms may lead to weight loss and dehydration.
Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD