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Giardia lamblia exists as both cysts & trophozoites (mature form by which the protozoon is transmitted). The organism colonizes and multiplies within the upper small intestine and may lead to intestinal damage. This damage could lead to steatorrhea and traveler's diarrhea.

Clinical manifestations

The incubation period is about two weeks (range 5 days to 20 days), but it can be much longer.

Many patients have no symptoms at all. Main complaints are intermittent diarrhea, steatorrhea, malabsorption, stomach pains, bloating, flatulence, and some nausea and vomiting.


Stool microscopy reveals cysts in most patients.


Metronidazole is effective in eradicating the disease. A repeat stool microscopy test 2 months after the initiation of therapy provides a good test for cure.





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