1. Cyst forms found in the feces .......... Go to: 3 & 4
2. Trophs (active forms) found in diarrhetic stool, intestinal scrapings, or mucosal impressions ........ Go to: 9 & 10

3 Small oval cyst containing 4 round nuclei at one end and dark lines (axostyle & median bodies) extending through the cyst. Cyst wall is not distinctly refractile. Usually seen during a direct (saline) fecal exam .......... Giardia sp.
4. Cysts (medium, small or very small) with distinct refractile cyst wall, may be unsporulated or sporulated. But does not contain distinct cellular organelles. Usually seen during a (simple or saturated sugar) floatation .......... Go to: 5, 6, 7 & 8

5. Round to oval medium-sized cysts (oocyst), may be flat on one end. Seen during fecal floatation. Unsporulated: oocyst contains a single cell. Sporulated (Cultured): oocyst contains 2 sporocysts .......... Isospora sp.
6. Small oval cysts (naked sporocysts) that contain 4 sporozoites, and many round refractile inclusions (sporocyst residium). .......... Sarcocystis sp.
7. Small round cysts. Unsporulated: oocyst contains a single cell. Sporulated: oocyst contains 2 sporocysts that contain 4 sporozoites. .......... Toxoplamsa gondii
8. Very small cysts that require acid-fast staining to verify identification .......... Cryptosporidium sp.

9. A small tear-shaped or pear-shaped flagellate with 2 nuclei and an dark line (axostyle) within the cell. Lacks an undulating membrane. (The organism slowly "wobbles" around the slide) .......... Giardia sp.
10. A small tear-shaped flagellate with 1 nuclei and an dark line (axostyle) within the cell. Possesses an undulating membrane (The organism moves quickly around the slide.) .......... Tritrichomonas foetus