1. Other Human Amoebae
Entamoeba dispar/E. hartmanni: Non pathogenic; anatomically indistinguishable from E. histolytica.

2. Entamoeba coli
Trophozoite Cyst Nucleus

3. Entamoeba coli
Life cycle and location identical to E. histolytica.

4. Entamoeba coli
Life cycle and location identical to E. histolytica.
Most common endocommensal in people; has a worldwide distribution and 10-50% of the population can be infected in different parts of the world.

5. Entamoeba coli Not pathogenic.
Life cycle and location identical to E. histolytica.
Most common endocommensal in people; has a worldwide distribution and 10-50% of the population can be infected in different parts of the world.
Not pathogenic.

6. Entamoeba coli
Life cycle and location identical to E. histolytica.
Most common endocommensal in people; has a worldwide distribution and 10-50% of the population can be infected in different parts of the world.
Not pathogenic.
Feeds on bacteria and any other cells available to it; does not invade tissue.

7. Other Hosts
Monkeys
Apes
Pigs

8. 10 mm
Trophozoites μm in diameter (15-50 µm)

9. A B C D
10 mm

10. E. coli
E. histolytica A B C D
10 mm

11. C
Cysts μm
10 mm

12. Entamoeba gingivalis Habitat: Mouth
Habitat: Mouth
Hosts: Humans, other primates, dogs and cats.
Prevalence is from 50 to 95%.
Stage: Trophozoite, no cyst.

13. Entamoeba gingivalis
Trophozoite lives on the surface of teeth and gums. Feed on epithelial cells of the mouth, bacteria, food debris, and other cells available to them.

14. Entamoeba gingivalis
Trophozoite lives on the surface of teeth and gums. Feed on epithelial cells of the mouth, bacteria, food debris, and other cells available to them.
Organisms are more common in persons with pyorrhea (gum disease) but they are not the cause of the condition.

15. Entamoeba gingivalis
Trophozoite lives on the surface of teeth and gums. Feed on epithelial cells of the mouth, bacteria, food debris, and other cells available to them.
Organisms are more common in persons with pyorrhea (gum disease) but they are not the cause of the condition.
Transmission mouth to mouth, droplet spray, or sharing eating utensils.

16. Endolimax nana “The dwarf internal slug”
Trophozoite Cyst Nucleus

17. Endolimax nana
Second most common endocommensal of humans, worldwide distribution 30%.

18. Endolimax nana
Second most common endocommensal of humans, worldwide distribution 30%.
Lives in the large intestine mainly near the cecum and feed on bacteria; non pathogenic.

19. Endolimax nana Also occurs in monkeys.
Second most common endocommensal of humans, worldwide distribution 30%.
Lives in the large intestine mainly near the cecum and feed on bacteria; non pathogenic.
Also occurs in monkeys.

20. Trophozoites are tiny 6-15 μm in diameter.
Large glycogen vacuoles are often present.
10 mm

21. Mature cyst is 5 – 14 μm in diameter; contains 4 nuclei; shape is round to elliptical
10 mm

22. Iodamoeba buetschlii
Trophozoite Cyst Nucleus

23. Iodamoeba buetschlii
Not very common endocommensal in people.

24. Iodamoeba buetschlii
Not very common endocommensal in people.
Lives in the large intestine, predominantly in the cecal areas.

25. Iodamoeba buetschlii
Not very common endocommensal in people.
Lives in the large intestine, predominantly in the cecal areas.
Has a very high prevalence in pigs; 50% of pigs are infected with this ameba in France and Egypt; pigs are probably its normal host.

26. Trophozoites are 9-14 μm long but may be as large as 20μm
10 mm

27. 10 mm

28. E. nana
10 mm
I. buetschlii

29. Cysts are 6-15 µm long and have a large glycogen vacuole.
10 mm

30. Dientamoeba fragilis
Trophozoite No Cyst Nucleus

31. Dientamoeba fragilis
LIFE CYCLE - it does not form cysts and trophozoites cannot survive passage through the small intestine.

32. Dientamoeba fragilis
LIFE CYCLE - it does not form cysts and trophozoites cannot survive passage through the small intestine.
Humans probably get infected by this endocommensal when they ingest pinworm eggs!

33. Trophozoites small 6-12 µm long; binucleated.
10 mm