1. Amoeba: Formally Phylum Sarcodina R & J Ch 7
Protozoa with pseudopodia (or if not, distinct locomotive protoplasmic flow present).
Mitochondria when present never in the form of a kinetoplasts.
Without apical complex.
Without axostyles.

2. Amoeboid Movement
Amoeboid locomotion is used by certain protists including parasitic amoeba.

3. Complex changes in cell fine structure, chemistry, and behavior.
(gel-like)
(more fluid)

4. Mechanisms of Amoeboid Movement

5. Mechanisms of Ameboid Movement

6. Amoeba Diversity
Most amoebas are harmless single cell protozoans living in mud, water, and soil feeding on other protozoans and bacteria.
Some species are parasitic and endocommensals and are quite common inhabitants of animals.

7. Endocommensal and Parasitic Amoeba Diversity
Domestic animals
Birds are free
Reptiles  one species that is pathogenic in snakes Entamoeba invadens
Frogs and salamanders
Leeches, termites, and cockroaches
Hydra
Humans

8. Some Amoeba are Pathogenic
Amebiasis- The pathological condition of having an amoebic infection.
-iasis- “indicates a pathological condition”

9. Entamoeba histolytica

10. Entamoeba histolytica
One of the most important and pathogenic parasites of humans.

11. Entamoeba histolytica
One of the most important and pathogenic parasites of humans.
Although dogs, cats and primates may be infected, these infections are rare and unimportant. This parasite is primarily a human parasite and is transmitted from human to human.

12. Entamoeba histolytica
One of the most important and pathogenic parasites of humans.
Although dogs, cats and primates may be infected, these infections are rare and unimportant. This parasite is primarily a human parasite and is transmitted from human to human.
First seen in 1878 but not described until 1903.

13. Entamoeba histolytica
One of the most important and pathogenic parasites of humans.
Although dogs, cats and primates may be infected, these infections are rare and unimportant. This parasite is primarily a human parasite and is transmitted from human to human.
First seen in 1878 but not described until 1903.
Causative agent of the disease amebiasis (old name is Amoebic Dysentery).

14. Entamoeba histolytica

15. Entamoeba histolytica
Active, feeding stage
Growing stage
Amoeboid with blunt pseudopodia
Non-foamy cytoplasm
Uninucleated; nucleus with fine peripheral chromatin granules, small central endosome
Trophozoite: µm

16. Entamoeba histolytica Trophozoites

17. Entamoeba histolytica
Dormant/resistant stage
Spherical
1-4 nuclei, (4 in mature cysts)
Bluntly rounded chromatoidal bars
Cyst:10-20 μm

18. Entamoeba histolytica Cysts

19. Entamoeba histolytica Cysts
Uninucleate cyst Binucleate cyst

20. Entamoeba histolytica Cysts
Quadrinucleate or mature cysts

21. Entamoeba histolytica Life Cycle

22. Entamoeba histolytica Life Cycle
INFECTIVE STAGE: Cyst

23. Entamoeba histolytica Life Cycle
INFECTIVE STAGE: Cyst
Cysts are susceptible to heat (above 40 °C), freezing (below –5 °C), and drying.

24. Entamoeba histolytica Life Cycle
INFECTIVE STAGE: Cyst
Cysts are susceptible to heat (above 40 °C), freezing (below –5 °C), and drying.
Cysts remain viable in moist environment for 1 month.

25. Entamoeba histolytica Life Cycle
CYST: ingested with fecal contaminated food or water.

26. Entamoeba histolytica Life Cycle
CYST: ingested with fecal contaminated food or water.
Excystation occurs in the small intestine in an alkaline environment.

27. Entamoeba histolytica Life Cycle
CYST: ingested with fecal contaminated food or water.
Excystation occurs in the small intestine in an alkaline environment.
Metacystic amoebas emerge, divide and move down into the large intestine.

28. Entamoeba histolytica Life Cycle
Trophozoites colonize the large intestine and invade the mucosa.

29. Entamoeba histolytica Life Cycle
Trophozoites colonize the large intestine and invade the mucosa.
They live within the crypts and mucosa of the large intestinal lining.

30. Entamoeba histolytica Life Cycle
Trophozoites colonize the large intestine and invade the mucosa.
They live within the crypts and mucosa of the large intestinal lining.
Trophozoites may live and multiply indefinitely within the crypts of the LI mucosa feeding on starches and mucous secretions.

31. Entamoeba histolytica Life Cycle
Cysts form in response to unfavorable (deteriorating) environmental conditions, as they move down the LI.

32. Entamoeba histolytica Life Cycle
Cysts form in response to unfavorable (deteriorating) environmental conditions, as they move down the LI.
They are released in formed feces.

33. Entamoeba histolytica
E. histolytica has surface enzymes that can digest epithelial cells and therefore hydrolyze host tissues and cause pathology.

34. Entamoeba histolytica
E. histolytica has surface enzymes that can digest epithelial cells and therefore hydrolyze host tissues and cause pathology.
Usually the hosts’ repair of the epithelial cells can keep pace with the damage.

35. Entamoeba histolytica
E. histolytica has surface enzymes that can digest epithelial cells and therefore hydrolyze host tissues and cause pathology.
Usually the hosts’ repair of the epithelial cells can keep pace with the damage.
However, when the host is stressed, has too much HCl, or a high bacterial flora, the digestion will be ahead of repair.

36. Entamoeba histolytica Pathology
1. A Primary Ulcer can occur.

37. Entamoeba histolytica Pathology
1. A Primary Ulcer can occur.
Flask Shaped Ulcers

38. Entamoeba histolytica Pathology
1. A Primary Ulcer can occur.
A primary ulcer can cause rupturing of the bowel and can cause Peritonitis.

39. Shows movement of trophozoites from large intestine to liver via hepatic portal vein.
Liver Abscesses

40. Entamoeba histolytica Pathology
Extra-Intestinal Lesions and Abscess Occurs

41. Entamoeba histolytica Pathology
Extra-Intestinal Lesions and Abscess Occurs
A. Hepatic Amebiasis

42. Entamoeba histolytica Pathology
Extra-Intestinal Lesions and Abscess Occurs
A. Hepatic Amebiasis
B. Pulmonary Amebiasis

43. Entamoeba histolytica Pathology
Extra-Intestinal Lesions and Abscess Occurs
A. Hepatic Amebiasis
B. Pulmonary Amebiasis
C. Cerebral Amebiasis

44. Entamoeba histolytica Pathology
Frequently, intestinal lesions will heal themselves.

45. Entamoeba histolytica Pathology
Frequently, intestinal lesions will heal themselves.
Two exceptions- External ulcers that did not come from the intestine.
Ocular amebiasis
Genital amebiasis

46. Amoebic Amebiasis of the Skin

47. Symptoms
10% of people in the world infected with ameba, but only 3% ever have some sort of clinical signs.

48. Symptoms Abdominal discomfort.
10% of people in the world infected with ameba, but only 3% ever have some sort of clinical signs.
Abdominal discomfort.

49. Symptoms Intense pain localized on the right side.
10% of people in the world infected with ameba, but only 3% ever have some sort of clinical signs.
Abdominal discomfort.
Intense pain localized on the right side.

50. Symptoms
10% of people in the world infected with ameba, but only 3% ever have some sort of clinical signs.
Abdominal discomfort.
Intense pain localized on the right side.
Dysentery.

51. So How Bad is This? In theory, ingestion of 1 cyst could kill you.
In practice, probably it will never happen.

52. Prognosis 90% of time recovery. - How much damage.
- Body will repair itself but this repaired
connective tissue in bowel will not
function.

53. Diagnosis Fecal smear/Nested PCR and monoclonal antibody methods.
Biopsy.
Serological/Immunological tests (ELISA).

54. Seriousness of Diagnosis
Could expose someone to unnecessary treatment.
Will not be treating the real problem.
There is an expense.
Time factor.

55. Treatment Current drug of choice  Metronidazole (Flagyl).
Side effects: Insomnia, headaches, vomiting, intense vasodilation, mutations on bacteria, and carcinogenic in mice.

56. Epidemiology
How an infectious organism spreads through a population.

57. Entamoeba histolytica
DISTRIBUTION - Parasite has worldwide distribution but is most common in the tropical and subtropical areas of the world.

58. Entamoeba histolytica
DISTRIBUTION - Parasite has worldwide distribution but is most common in the tropical and subtropical areas of the world.
 - it is estimated that up to 500 million people may be affected.
 - may cause up to 100,000 deaths each year.

59. Entamoeba histolytica
DISTRIBUTION - Parasite has worldwide distribution but is most common in the tropical and subtropical areas of the world.
 - it is estimated that up to 500 million people may be affected.
 - may cause up to 100,000 deaths each year.
PREVALENCE: < 1% in Canada and Alaska
0.9% in U.S.
40% in the tropics

60. Entamoeba histolytica
A number of outbreaks have resulted from a breakdown in sanitation or behavioral practices of people.

61. Entamoeba histolytica
A number of outbreaks have resulted from a breakdown in sanitation or behavioral practices of people.
Outbreak in 1933 World's Fair in Chicago caused by defective plumbing (cross connections between water lines and sewer lines) caused over 1,000 cases of amebiasis resulting in 58 deaths.

62. Entamoeba histolytica
A number of outbreaks have resulted from a breakdown in sanitation or behavioral practices of people.
Outbreak in 1933 World's Fair in Chicago caused by defective plumbing (cross connections between water lines and sewer lines) caused over 1,000 cases of amebiasis resulting in 58 deaths.
Outbreak in the late 1970’s in New York City among gay men.