A 5-year-old presents with perianal pruritus worse at night. Scotch tape applied perianally shows D-shaped (one side flattened) eggs. The mode of transmission of this parasite is:
- A Larval penetration of intact skin
- B Ingestion of embryonated eggs via feco-oral route ✓
- C Ingestion of undercooked pork containing cysticerci
- D Bite of sandfly
Correct answer: B. Ingestion of embryonated eggs via feco-oral route
Explanation
Enterobius vermicularis (pinworm) is transmitted by ingestion of embryonated eggs via the feco-oral route. Unlike soil-transmitted helminths, no external development period is required — eggs become infective within 6 hours of deposition. The female worm migrates to the perianal region at night to deposit eggs, causing intense pruritus. Auto-infection (hand-to-mouth) and hetero-infection are common. The scotch tape (Graham's sellotape) test is the diagnostic method of choice, detecting the characteristic asymmetric D-shaped eggs.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.