An egg with four cells in the developing embryo within a thin-shelled egg is most consistent with which parasite?

• A. Strongyloides stercoralis
• B. Trichuris trichiura
• C. Hookworm
• D. Enterobius vermicularis

Answer: (C)

Eggs that are thin-shelled and contain a developing embryo at the four-cell stage point to hookworm. Hookworm eggs in stool are oval with a delicate, translucent shell, and early embryonation often shows a 4-cell cleavage before the larva forms. This distinguishes them from other common intestinal nematode eggs: Trichuris eggs have thick shells with polar plugs; Enterobius eggs are thin-walled and typically unembryonated when first detected and have a flattened side; Strongyloides usually presents larvae (rhabditiform) rather than a clearly visible four-cell embryo inside an egg. So the described egg pattern best matches hookworm.