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Giardia Lamblia »

What is giardiasis?

Giardiasis (gee-ar-die-a-sis with a soft "G") is an infection of the small intestine that is caused by the parasite, Giardia intestinalis, also known as Giardia lamblia. It is the most common cause of parasitic gastrointestinal disease; it is estimated that up to 2.5 million cases of giardiasis occur each year in the U.S., and up to 20% of the world's population is chronically infected.

Giardia lamblia exists in two forms, an active form called a trophozoite, and an inactive form called a cyst. The active trophozoite attaches to the lining of the small intestine with a "sucker" and is responsible for causing the signs and symptoms of giardiasis. The trophozoite cannot live long outside of the body, therefore it cannot spread the infection to others. The inactive cyst, on the other hand, can exist for prolonged periods outside the body. When it is ingested, stomach acid activates the cyst, and the cyst develops in...

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