An egg about 38 μm in diameter with a thick shell containing radial striations and several hooklets is seen in a wet mount. What is the most likely identification of the egg?

• A. Hymenolepis nana
• B. Schistosoma japonicum
• C. Hymenolepis diminuta
• D. Taenia sp.

Answer: (D)

Recognizing cestode eggs on a wet mount depends on shell pattern, size, and the embryo inside. An egg around 38 μm in diameter with a thick shell that shows radial striations and contains a hexacanth embryo with several hooklets fits Taenia species very well. The thick, radially striated shell is a classic feature of Taenia eggs, and the hooklets within the embryo (the six-hook oncosphere) are a key identifying trait. Other eggs, like Hymenolepis species, typically lack these prominent radial striations and hooklet presentation, and Schistosoma japonicum eggs have different morphology altogether (they are not thick-shelled cestode eggs and have a distinct spine). So the most likely identification is Taenia species.