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Entamoeba histolytica

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  • 1. GIT protozoa
  • 2. INTESTINAL PROTOZOA Ameba: Entamoeba histolytica Entamoeba dispar Entamoeba coli Entamoeba hartmanni Endolimax nana Iodamoeba bütschlii Flagellates: • Giardia lamblia • Dientamoeba fragilis • Chilomastix mesnili • Trichomonas hominis • Trichomonas vaginalis •(other body sites) • Enteromonas hominis • Retortamonas intestinalis Apicomplexa: • Cryptosporidium hominis • Cryptosporidium parvum Other: • Blastocystis hominis • Balantidium coli unicellular eukaryotic organisms
  • 3. Ameba: Formally Phylum Sarcodina • 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.
  • 4. Ameba 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.
  • 5. Endocommensal and Parasitic Ameba 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
  • 6. Some Ameba are Pathogenic • Amebiasis- The pathological condition of having an amoebic infection. • -iasis- “indicates a pathological condition”
  • 7. Entamoeba histolytica
  • 8. Entamoeba histolytica • One of the most important and pathogenic parasites of humans.
  • 9. 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.
  • 10. 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.
  • 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. • First seen in 1878 but not described until 1903. • Causative agent of the disease amebiasis (old name is Amebic Dysentery).
  • 12. Entamoeba histolytica
  • 13. Entamoeba histolytica Trophozoite: 20-30 µm • Active, feeding stage • Growing stage • Amoeboid with blunt pseudopodia • Non-foamy cytoplasm • Uninucleated; nucleus with fine peripheral chromatin granules, small central endosome
  • 14. Entamoeba histolytica Trophozoites
  • 15. Entamoeba histolytica • Dormant/resistant stage • Spherical • 1-4 nuclei, (4 in mature cysts) • Bluntly rounded chromatoidal bars Cyst:10-20 μm
  • 16. Entamoeba histolytica Cysts
  • 17. Entamoeba histolytica Cysts Uninucleate cyst Binucleate cyst
  • 18. Entamoeba histolytica Cysts Quadrinucleate or mature cysts
  • 19. Ameboid Movement • Ameboid locomotion is used by certain protists including parasitic amoeba.
  • 20. Complex changes in cell fine structure, chemistry, and behavior. (gel-like) (more fluid)
  • 21. Mechanisms of Ameboid Movement
  • 22. Mechanisms of Ameboid Movement
  • 23. Entamoeba histolytica Life Cycle
  • 24. Entamoeba histolytica Life Cycle • INFECTIVE STAGE: Cyst
  • 25. Entamoeba histolytica Life Cycle • INFECTIVE STAGE: Cyst • Cysts are susceptible to heat (above 40 °C), freezing (below –5 °C), and drying.
  • 26. 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.
  • 27. Entamoeba histolytica Life Cycle • CYST: ingested with fecal contaminated food or water.
  • 28. Entamoeba histolytica Life Cycle • CYST: ingested with fecal contaminated food or water. • Excystation occurs in the small intestine in an alkaline environment.
  • 29. Entamoeba histolytica Life Cycle • CYST: ingested with fecal contaminated food or water. • Excystation occurs in the small intestine in an alkaline environment. • Metacystic amebas emerge, divide and move down into the large intestine.
  • 30. Entamoeba histolytica Life Cycle • Trophozoites colonize the large intestine and invade the mucosa.
  • 31. 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.
  • 32. 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.
  • 33. Entamoeba histolytica Life Cycle • Cysts form in response to unfavorable (deteriorating) environmental conditions, as they move down the LI.
  • 34. 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.
  • 35. Entamoeba histolytica • E. histolytica has surface enzymes that can digest epithelial cells and therefore hydrolyze host tissues and cause pathology.
  • 36. 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.
  • 37. 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.
  • 38. Entamoeba histolytica Pathology 1. A Primary Ulcer Can Occur.
  • 39. Entamoeba histolytica Pathology 1. A Primary Ulcer Can Occur. Flask Shaped Ulcers
  • 40. Entamoeba histolytica Pathology 1. A Primary Ulcer Can Occur. A primary ulcer can cause rupturing of the bowel and can cause Peritonitis.
  • 41. Shows movement of trophozoites from large intestine to liver via hepatic portal vein. Liver Abscesses
  • 42. Entamoeba histolytica Pathology 2. Extra-Intestinal Lesions and Abscess Occurs
  • 43. Entamoeba histolytica Pathology 2. Extra-Intestinal Lesions and Abscess Occurs A. Hepatic Amebiasis
  • 44. Entamoeba histolytica Pathology 2. Extra-Intestinal Lesions and Abscess Occurs A. Hepatic Amebiasis B. Pulmonary Amebiasis
  • 45. Entamoeba histolytica Pathology 2. Extra-Intestinal Lesions and Abscess Occurs A. Hepatic Amebiasis B. Pulmonary Amebiasis C. Cerebral Amebiasis
  • 46. Entamoeba histolytica Pathology • Frequently, intestinal lesions will heal themselves.
  • 47. Entamoeba histolytica Pathology • Frequently, intestinal lesions will heal themselves. • Two exceptions- External ulcers that did not come from the intestine. Ocular amebiasis Genital amebiasis
  • 48. Amoebic Amebiasis of the Skin
  • 49. Symptoms • 10% of people in the world infected with ameba, but only 3% ever have some sort of clinical signs.
  • 50. Symptoms • 10% of people in the world infected with ameba, but only 3% ever have some sort of clinical signs. • Abdominal discomfort.
  • 51. 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.
  • 52. 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.
  • 53. So How Bad is This? • In theory, ingestion of 1 cyst could kill you. • In practice, probably it will never happen.
  • 54. Prognosis • 90% of time recovery. - How much damage. - Body will repair itself but this repaired connective tissue in bowel will not function.
  • 55. Diagnosis • Fecal smear/Nested PCR and monoclonal antibody methods. • Biopsy. • Serological/Immunological tests (ELISA).
  • 56. Seriousness of Diagnosis • Could expose someone to unnecessary treatment. • Will not be treating the real problem. • There is an expense. • Time factor.
  • 57. Treatment • Current drug of choice  Metronidazole (Flagyl). • Side effects: Insomnia, headaches, vomiting, intense vasodilation, mutations on bacteria, and carcinogenic in mice.
  • 58. Epidemiology • How an infectious organism spreads through a population.
  • 59. Entamoeba histolytica DISTRIBUTION - Parasite has worldwide distribution but is most common in the tropical and subtropical areas of the world.
  • 60. 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.
  • 61. 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.
  • 62. Entamoeba histolytica • A number of outbreaks have resulted from a breakdown in sanitation or behavioral practices of people.
  • 63. Management • Metronidazole 800 mg three times daily for 5 days is given in amoebic colitis; a lower dose (400 mg three times daily for 5 days) is usually adequate in liver abscess. • Tinidazole is also effective: dehydroemetine and chloroquine are alternative drugs, but are rarely used. After treatment of the invasive disease, the bowel should be cleared of parasites with a luminal amoebicide such as diloxanide furoate.
  • 64. Prevention • Amoebiasis is difficult to eradicate because of the substantial human reservoir of infection. The only progress will be through improved standards of hygiene and better access to clean water. • Cysts are destroyed by boiling, but chlorine and iodine sterilizing tablets are not always effective.