Amoebiasis pathogenesis and pathology

ethiology , pathogenesis and pathology of intestinal amoebiasis, amoebic liver abscess and pulmonary amoebic abscess

1. Pathogenesis & Pathology of Amoebiasis By Abhishek Udaykumar 004

2. Causative agent : Entamoeba histolytica Routes of infection: Food and water contaminated by faeces Oral and anal sexual practices. Ethiology

3. Factors determining pathogenesis 1)Strain Entamoeba dispar is similar to Entamoeba histolytica but differ in virulence 2)virulence Virulent strains are capable of transformation into invasive due to Adherence and colonization Enterotoxin production Contact dependant cell lysis Proteolytic enzyme secretion Pathogenesis

4. 3)Host factors Decreased Immunity Mal Nutrition Immunosuppressive Drugs Condition of intestinal mucosa

5. Ingestion of cyst excystation in small intestine production of throphozoites multiplication and colonization of large intestine Intestinal lesions Pathogenesis

6. Extension through muscularis mucosa and sub mucosa Ulcer formation (flask shape) Thrombosis of blood vessels Toxic megacolon Necrosis of bowel wall

7. Pathogenesis of amoebic liver abscess

8. Can develop in the following ways: Rupture of amoebic hepatic abscess through diaphragm(most common) Lymphatic spread from liver through diaphragm Haematogenous spread. Pulmonary amoebiasis

9. Cerebral amoebiasis rare complication of hepatic or pulmonary abscess due to haematogenous spread Cutaneous amoebiasis Urogenital tract amoebiasis Other manifestations

10. Complications of amoebiasis

11. Gross pathology Intestinal lesions appear as elevation on mucosal surface Amoebic colitis : Flask shaped ulcer with narrow neck due to lytic action of trophozoites and broad necrotic bed seen Amoeboma :inflammatory thickening of wall of large bowel resembling carcinoma colon. Pathology of intestinal amoebiasis

12. Lesions with granulation tissue seen Fibrosis and clusters of throphozoites seen at margin of necrotic tissue microscopy

13. Amoebic liver abscess are usually solitary and are more often located on right lobe in posterosuperior part Greatly vary in size, usually about the size of an orange Centre consists of large necrotic area having reddish brown pus resembling ‘anchovy sauce’ Abscess wall consists of irregular shreds of necrotic liver tissue Amoebic liver abscess

14. Necrotic area consists of degenerated liver cells ,leucocytes, red blood cells, connective tissue and debris Amoeba can be observed in liver parenchyma at the margin of abscess microscopy