A farmer living near a lake in rural China presents with focal seizures. MRI shows granulomatous lesions in the brain. Stool examination reveals numerous small, round eggs with a minute lateral knob but no true spine. Which feature of this parasite best explains cerebral involvement being more frequent than in other human schistosomes?

• A It produces the highest egg output per paired worm burden ✓
• B Its eggs are the largest among schistosome eggs, embolising readily
• C Its adult worms migrate directly into cerebral venous sinuses
• D Its cercariae penetrate the intact scalp during bathing

Explanation

Schistosoma japonicum worms produce ten times more eggs than Schistosoma mansoni, and its smaller, round eggs with only a vestigial knob disseminate widely via the bloodstream, making cerebral and ectopic deposition far more common than in other species. Cerebral schistosomiasis presents as seizures from granulomas around deposited eggs. Adult worms remain in the mesenteric venules and do not enter cerebral vessels, cercariae penetrate exposed skin anywhere, and its eggs are actually the smallest of the human schistosome eggs.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.