E.histolytica

Question 1

What is the infective stage of Entamoeba histolytica?

Answer 1

Quadrinucleate cyst.

Question 2

What is the active stage of Entamoeba histolytica?

Answer 2

Trophozoite.

Question 3

Where is the habitat of Entamoeba histolytica?

Answer 3

Colon (cecum & recto-sigmoidal region).

Question 4

What is the mode of transmission of Entamoeba histolytica?

Answer 4

Fecal-oral route.

Question 5

What are the primary and secondary sites of infection?

Answer 5

Primary: Intestinal; Secondary: Extra-intestinal.

Question 6

Who is the definitive host of Entamoeba histolytica?

Answer 6

Humans.

Question 7

What are the two forms of intestinal amebiasis?

Answer 7

Dysenteric (Acute) and Non-dysenteric (Chronic).

Question 8

What are the diagnostic methods for Entamoeba histolytica?

Answer 8

Stool analysis, Endoscopy, PCR, Serology (ELISA, IFA, IHA).

Question 9

What is the treatment for Entamoeba histolytica?

Answer 9

Metronidazole, followed by luminal amebicides (Diloxanide furoate, Iodoquinol, Paromomycin).

Question 10

Where does excystation occur?

Answer 10

Terminal small intestine.

Question 11

What is the meaning of the name ‘Entamoeba histolytica’?

Answer 11

Ent=intestine, Ameba=Ameba, Histo=tissue, Lytica=lysis (dissolve).

Question 12

What is the geographical distribution of Entamoeba histolytica?

Answer 12

Worldwide, but more common in tropical areas with poor sanitation.

Question 13

What is the second leading cause of death due to parasitic diseases?

Answer 13

Entamoeba histolytica.

Question 14

What are the five morphological stages of Entamoeba histolytica?

Answer 14

Trophozoite, Cyst, Metacyst, Precyst, Metacystic Trophozoite.

Question 15

Which two stages are clinically important?

Answer 15

Trophozoite and Cyst.

Question 16

How can E. histolytica be differentiated from E. dispar?

Answer 16

By enzyme analysis (cysteine protease), molecular techniques (PCR), and absence of ingested RBCs.

Question 17

What are the characteristics of the cyst stage?

Answer 17

Round or oval, 1-4 nuclei (4 in mature cysts), Chromatoidal bars with RNA & DNA, resistant to chlorine, viable in water for 30 days.

Question 18

What conditions kill Entamoeba histolytica cysts?

Answer 18

Temperature below 5°C or above 40°C, putrefaction, and desiccation.

Question 19

What is the pathogenesis of Entamoeba histolytica dependent on?

Answer 19

Strain virulence, host resistance, intestinal conditions (hypomotility, bacterial colonization).

Question 20

What percentage of infections are asymptomatic?

Answer 20

85-95% (Cyst passers).

Question 21

What is the most common extra-intestinal site of infection?

Answer 21

Liver (Hepatic Amebiasis).

Question 22

What are the complications of intestinal amebiasis?

Answer 22

Appendicitis, intestinal hemorrhage, perforation, obstruction, fulminant colitis, amoeboma, rectal ulcers.

Question 23

What is a characteristic lesion in acute intestinal amebiasis?

Answer 23

Flask-shaped ulcers in the colonic mucosa.

Question 24

What is the incubation period of acute intestinal amebiasis?

Answer 24

1-4 weeks.

Question 25

What is the characteristic symptom of amoebic dysentery?

Answer 25

Foul-smelling stools containing blood and mucus, tenesmus, fever.

Question 26

How can amoebic dysentery be differentiated from bacillary dysentery?

Answer 26

Amoebic dysentery has offensive odor, acidic pH, many RBCs, few polymorphs, and Charcot-Leyden crystals.

Question 27

What is amoeboma?

Answer 27

A chronic granulomatous lesion in the cecum or rectosigmoid region, causing bowel stricture.

Question 28

What is the characteristic finding of hepatic amebiasis?

Answer 28

Single or multiple liver abscesses with 'anchovy sauce' appearance.

Question 29

What are the complications of hepatic amebiasis?

Answer 29

Peritonitis, amebic cutis, pulmonary amebiasis, pericarditis, secondary bacterial infection.

Question 30

What is the recommended diagnostic test for hepatic amebiasis?

Answer 30

Serological tests (ELISA, IHA, PCR), Ultrasound, CT scan, aspiration if necessary.

Question 31

What is the first-line drug for amebiasis?

Answer 31

Metronidazole (Flagyl).

Question 32

What should follow metronidazole treatment?

Answer 32

Luminal amebicide (Diloxanide furoate, Iodoquinol, Paromomycin).

Question 33

What are the side effects of metronidazole?

Answer 33

Metallic taste, nausea, headache, vomiting.

Question 34

What is contraindicated with metronidazole use?

Answer 34

Alcohol (causes intense vasodilation, vomiting, headache), pregnancy.

Question 35

What are preventive measures for amebiasis?

Answer 35

Personal hygiene, treatment of carriers, avoiding polluted water, proper washing of fruits/vegetables, protecting food from flies and cockroaches.