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Amebiasis is a parasitic infection caused by Entamoeba histolytica, an intestinal protozoan. It manifests as asymptomatic colonization, invasive intestinal disease (colitis, dysentery), or extraintestinal disease (most commonly liver abscess).

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https://www.youtube.com/watch?v=wBPh9svlU9Q

https://www.youtube.com/watch?v=vA26UI_htIU

Etiopathogenesis

• Agent: Entamoeba histolytica (pathogenic). Nonpathogenic strains include E. dispar and E. moshkovskii.
• Transmission: Feco-oral route via ingestion of cysts in contaminated food/water.

Pathology:

https://www.youtube.com/watch?v=Xti6OURHxhc

• Cysts release trophozoites in the small intestine → invade colonic mucosa → flask-shaped ulcers.
• Hematogenous spread (via portal vein) → liver abscess (most common extraintestinal manifestation).
• Rare spread to lungs, brain, or skin.

Clinical Features

Intestinal Amebiasis:

• Dysentery, abdominal pain, tenesmus, chronic diarrhea, weight loss.

Extraintestinal Amebiasis:

• Liver abscess: Fever, right upper quadrant pain, hepatomegaly, tender liver, cough (if diaphragmatic irritation).
• Lung involvement: pleural effusion, empyema.
• Rare CNS disease.