A 28-year-old man returns from trekking in the Himalayas where he drank stream water directly. He complains of foul-smelling, greasy stools, bloating, cramping abdominal pain, and excessive flatus. Stool microscopy shows pear-shaped trophozoites with two nuclei, four pairs of flagella, and a falling-leaf motility. Which structure mediates attachment of this parasite to the intestinal mucosa?

• A Oral sucker
• B Rostellar hooks
• C Cytostome
• D Ventral adhesive disc ✓

Explanation

The clinical picture is classic giardiasis caused by Giardia duodenalis (lamblia). The trophozoite attaches to duodenal enterocytes using its concave ventral adhesive disc (sucking disc), producing mechanical obstruction and malabsorption with steatorrhoea. It lacks an oral sucker, cytostome and hooks, structures seen in trematodes and ciliates rather than flagellates.

Reference: Paniker's Textbook of Medical Parasitology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.