Answer to Case 416

Answer: Strongyloides stercoralis adult female worms containing eggs and rhabditiform larvae. A possible filariform larva is also seen.

Adults worms are almost never seen in the stool of patients with strongyloidiasis, but when present, indicate a likely heavy infection. This case is remarkable because eggs and larvae are seen within the adult worms, illustrating how quickly the eggs hatch in the normal life cycle of this worm. The adult female usually lays the eggs directly in the intestinal mucosa where they quickly hatch to release rhabditiform larvae. This is why larvae, and not eggs, are found in the stool of patients with S. stercoralis infection.

Thanks again to Boren for donating this fascinating case.