A székletben található Giardia ciszták
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Once an animal or person cdc giardia been infected with this protozoan, the cdc giardia lives in the intestine, and is passed in the stool. Because the parasite is protected by an outer shell, it can survive outside the body, and in the environment for long periods of time.
Cysts are resistant forms and are responsible for transmission of giardiasis.
Both cysts and trophozoites can be found in the feces diagnostic stages. The cysts are hardy and can survive several months in cold water.
Fájl:Giardia lamblia SEM 8698 lores.jpg
Infection occurs by the ingestion of cysts in contaminated water, food, or by cdc giardia fecal-oral route hands or fomites.
In the small intestine, excystation releases trophozoites each cyst produces two trophozoites. Trophozoites multiply by longitudinal binary fission, remaining in the lumen of the proximal cdc giardia bowel where they can be free or attached to the mucosa by a ventral sucking disk.
Encystation occurs as the parasites transit toward the colon. The cyst is the stage found most commonly in non-diarrheal feces. Because the cysts are infectious when passed in the stool or shortly afterward, person-to-person transmission is possible. While cdc giardia are infected with Giardia, their importance as a reservoir is unclear.