Life Cycle of Giardia

1-2. Giardia cysts are injested by consuming contaminated food or water, or fecorally.

3. When they are digested, the low pH of the stomach acid produces excystation, activated flagella breaks through the cell wall. Excystation releases trophozoites, with each cysts produces two trophozoites.

4. In the small instestine, the trophozoites reproduce asexually or float free or are attached to the mucosa of the lumen.

5. Both cysts and trophozoites are then passed in the feces, and are infectious. Person to person transmission is possible.