A 9-year-old boy from a hilly area presents with foul-smelling, greasy stools and flatulence for three weeks. Stool microscopy shows pear-shaped trophozoites, each with two nuclei and four pairs of flagella. The structure that allows this parasite to adhere to the duodenal mucosa is:
- A Cytostome
- B Ventral adhesive disc ✓
- C Undulating membrane
- D Axostyle
Correct answer: B. Ventral adhesive disc
Explanation
Giardia lamblia trophozoites attach to duodenal enterocytes using a ventral adhesive (sucking) disc, producing malabsorption and steatorrhoea without invasion. The cytostome is a feeding organelle of ciliates such as Balantidium coli, the undulating membrane belongs to Trichomonas, and the axostyle is a supporting rod in Trichomonas. Recognising the binucleate, flagellate trophozoite identifies Giardia, whose cyst is the infective form.
Reference: Paniker's Textbook of Medical Parasitology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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