Question:
Flask-shaped ulcers in the intestine are caused by which of the following?
Flask-shaped ulcers in the intestine are caused by which of the following?
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The parasite seen with ingested red blood cells in stool causes this classic ulcer.
Updated On: Jun 23, 2026
- Giardia lamblia
- Entamoeba histolytica
- Helicobacter pylori (H. pylori)
- E. vermicularis
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The Correct Option is B
Solution and Explanation
Step 1: Flask-shaped ulcers are the classic intestinal lesion of amoebiasis caused by Entamoeba histolytica.
Step 2: Disease begins when the amoeba contacts the cells lining the intestine and secretes the same enzymes it uses to digest bacteria, including substances that destroy cell membranes and proteins.
Step 3: This causes penetration and digestion of the host tissue, producing ulcers that are narrow at the mucosal surface and broad at the base - the typical flask shape.
Step 4: The trophozoite ingests dead cells and is often seen with red blood cells inside it (erythrophagocytosis) in stool. Giardia and E. vermicularis (pinworm) do not cause flask ulcers, and H. pylori causes gastric, not flask-shaped colonic, ulcers, so the answer is Entamoeba histolytica.
Step 2: Disease begins when the amoeba contacts the cells lining the intestine and secretes the same enzymes it uses to digest bacteria, including substances that destroy cell membranes and proteins.
Step 3: This causes penetration and digestion of the host tissue, producing ulcers that are narrow at the mucosal surface and broad at the base - the typical flask shape.
Step 4: The trophozoite ingests dead cells and is often seen with red blood cells inside it (erythrophagocytosis) in stool. Giardia and E. vermicularis (pinworm) do not cause flask ulcers, and H. pylori causes gastric, not flask-shaped colonic, ulcers, so the answer is Entamoeba histolytica.
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