The Giardia lamblia life cycle begins when cysts, the resistant forms of the parasite responsible for transmitting the diarrheal illness known as giardiasis, are accidentally ingested.

 

Once the parasite is in the small intestine, the Giardia lamblia life cycle continues as it releases trophozoites (protozoan in the active stage of its life cycle) that multiply and remain in the intestine. As the trophozoites mature in the intestine, they simultaneously migrate toward the colon, where they become thick-walled cysts again.

 

Giardia lamblia is often found in:

 

 

The Giardia lamblia life cycle can only be continued through ingestion of the parasite; you cannot become infected with Giardia lamblia through contact with blood.