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Tell me more about giardiasis.

Giardiasis (GEE-ar-DYE-uh-sis) is an intestinal infection cased by the microscopic parasite Giardia intestinalis (also known as Giardia lamblia). Giardia is frequently found in untreated water supplies, but people have also become infected from food, soil, and from objects contaminated by Giardia.

The Giardia parasite is surrounded by a hard, tough shell that protects it on its journey through the intestines and also when it is living in the environment. Recent studies have found giardia to be the main culprit in waterborne gastrointestinal disease outbreaks.

How is Giardia transmitted?

Giardia is transmitted through the fecal-oral route, where a person becomes infected by ingesting items contaminated with the Giardia parasite. This can occur via infected food or water, as well as coming into direct contact with Giardia-contaminated items. Giardia can survive in the environment for a very long time due to its protected shell, making it very good at causing waterborne outbreaks of gastrointestinal disease. Outbreaks in day care centers have also been reported.

What are the symptoms of giardiasis?

Most people infected with Giardia will show the following symptoms after approximately one to two weeks post-infection:

  • Diarrhea
  • Gas or flatulence
  • Greasy stools that float
  • Stomach cramps
  • Nausea/upset stomach

Symptoms can last for 2 to 6 weeks, occasionally longer. Some people infected with Giardia may not show any symptoms at all.

How is giardiasis treated?

There are several anti-parasitic medications used to treat giardiasis that are available by prescription only. If a person does not have diarrhea, treatment is not usually necessary, though it may be given to alleviate accompanying symptoms such as fatigue, loss of appetite, and nausea. It may also be given to asymptomatic persons if they are in the same household with persons who cannot take anti-Giardia medications.

How can I prevent giardiasis?

The best means of preventing giardiasis is through good handwashing techniques. If you are in a foreign country, it is advised to drink bottled water and avoid uncooked fruits and vegetables. At home, it is best to buy produce that can be cooked, peeled, and/or washed.

If you are currently experiencing symptoms of giardiasis, you should avoid swimming in water (including pools, rivers, lakes, streams, and the ocean) until you have been without symptoms for 2 weeks to avoid exposing other people.

CDC Info on Giardia: