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Flashcards in Amoebiasis Deck (30):
0

Causative organism of Amoebiasis?

Entamoeba histolytica.

1

What is Entamoeba histolytica?

Protozoan parasite.

2

How dangerous is Entamoeba histolytica to humans? (Kill many people?)

Leading parasitic cause of death in developing countries.

3

Where is E.histolytica found?

Cyst form can survive in the environment for weeks.
Found as an intestinal commensal in some people but does not seem to cause disease in those situations.

4

What can E.histolytica do to the body?

Cause ulcerative + inflammatory lesions of the colon.

5

What tissues can E.histolytica invade besides the colon?

Lungs, brain, liver.

6

Outline the life cycle of E.histolytica.

Trophozoite once in small bowel - active feeding stage
Cyst formed once organism reaches end of colon due to unfavorable conditions - excreted in faeces.

7

How does E.hostolytica make it to the intestines without being destroyed by the acidic pH of the stomach?

Cyst form is resistant to acid in the stomach.

8

How is E.histolytica transmitted?

Faecal-oral route.

9

Highly endemic area in SA with regards to E.histolytica?

Durban.

10

How does E.histolytica cause ulcerative and inflammatory lesions in the colon?

Trophozoites can lyse neutrophils > release toxic neutrophil products
*inflam. Cells found at periphery of amoebic lesions.

11

What kind of colonic lesions are associated with E.histolytica?

Non-specific mucosal thickening
Flask-shaped ulcers

12

What in the gut normally prevents against disease by E.histolytica?

Mucins in gut protect against amoebic adherence to the cell surface and their subsequent lysis.

13

Once one has had an E.histolytica infection can they get it again?

Immunity is normally protective so no.

14

What is the incubation time of E.histolytica?

1-3 weeks.

15

Clinical features of intestinal disease with E.histolytica?

Abdominal pain + tenderness
Bloody stool + Diarrhoea
Colitis
Decrease in faecal leucocytes

16

What are some unwanted complications with regards to an E.histolytica infection?

Toxic megacolon.
Perianal amoebiasis.
Amoeboma.

17

What is toxic mega colon due to with regards to E.histolytica?

Is a very dilated colon due to inappropriate steroid therapy.

18

Why may one administer inappropriate steroid therapy to someone with an E.histolytica infection?

May confuse it for inflam. bowel disease.

19

What is perianal amoebiasis with regards to E.histolytica?

Extension of severe bowel disease to skin or fistula us tracts.
May be ulcerative/ condylomatous .

20

How does one diagnose an E.histolytica infection?

Trophozoites and cysts in stool.
Trophozoites often have ingested RBC's
Serology

21

What are some clinical features of extra intestinal disease with E.histolytica?

Liver abscess.
Pleuropulmonery amoebiasis.
Cerebral amoebiasis.
Genitourinary amoebiasis.
Pericardial amoebiasis.

22

What is pleuropulmonery amoebiasis?

Complication of liver abscess >'rupture of liver lobe > hepatobronchial fistula
*sometimes sputum contains necrotic material or amoebae

23

What is pericardial amoebiasis?

Unusual complication of a liver abscess.

24

Comment on cerebral amoebiasis?

Unusual.
Quick death without treatment.

25

What are features of Genitourinary amoebiasis?

Painful granulomatous tissue ulcers
Rectovaginal fistulas > Trophozoites to Genitourinary tract

26

Diagnosis of extraintestinal illness with E.amoebiasis?

Serology.
Imaging techniques (CAT,MRI,ultrasound)
Aspiration: yellow-brown odorless liquid "anchovy paste"

27

How to treat an E.histolytica infection?

Metronidazole.
Treat symptomatic people and those with high risks of complications.

28

How to prevent E.histolytica transmission?

Good sanitation + hygiene
Vegetables commonly a source therefore wash them.
Boil water.
*chlorination may not always kill cysts

29

How to wash vegetables to prevent E.histolytica infection?

Veges > detergent soap > soak in vinegar
*kills cysts