A 9-year-old boy presents with recurrent foul-smelling, bulky stools and flatulence. Duodenal aspirate examination shows pear-shaped trophozoites with two nuclei, four pairs of flagella, and a concave ventral surface. The structure that allows this parasite to adhere to the intestinal mucosa is:
- A Buccal capsule with cutting plates
- B Ventral adhesive disc ✓
- C Rostellar hooks
- D Undulating membrane
Correct answer: B. Ventral adhesive disc
Explanation
The organism is Giardia lamblia. Its trophozoite bears a concave ventral adhesive (sucking) disc that attaches to the duodenal brush border, causing mechanical damage and malabsorption of fat and fat-soluble vitamins. The buccal capsule with cutting plates belongs to hookworms, rostellar hooks to Taenia solium, and the undulating membrane to trypanosomes and Trichomonas, none of which produce this picture.
Reference: Paniker's Textbook of Medical Parasitology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.