Which organism causes liver abscesses with anchovy paste and flask-shaped ulcers in the intestine, often acquired from contaminated water?

• A. Giardia lamblia
• B. Entamoeba histolytica
• C. Cryptosporidium
• D. Toxoplasma gondii

Answer: (B)

Entamoeba histolytica is an invasive intestinal protozoan acquired by ingesting cysts in contaminated water or food. In the colon, trophozoites penetrate the mucosa and create flask-shaped ulcers as they invade deeper tissue. Some trophozoites reach the portal circulation and seed the liver, forming amebic liver abscesses whose classic aspirate is described as anchovy paste due to necrotic debris and inflammatory cells. This combination of invasive colitis with flask-shaped ulcers and liver abscesses is characteristic and linked to contaminated-water transmission. Other organisms like Giardia lamblia cause noninvasive intestinal symptoms without liver abscess; Cryptosporidium causes severe watery diarrhea in immunocompromised individuals; Toxoplasma gondii typically affects the CNS and eyes, not producing amebic liver abscess or flask-shaped ulcers.