What is the primary diagnostic feature of Schistosoma haematobium eggs in urine?

• A. Operculated
• B. No spine
• C. Terminal spine
• D. Lateral spine

Answer: (C)

A large terminal (posterior) spine on the Schistosoma haematobium egg is the key diagnostic feature in urine. This spine sits at the far end of the egg and is highly distinctive, helping to identify urinary schistosomiasis caused by this species. In contrast, eggs of other schistosomes show different spine patterns: Schistosoma mansoni eggs have a prominent lateral spine, and Schistosoma japonicum eggs are more rounded with a small or less conspicuous lateral knob. Some trematode eggs are operculated, but Schistosoma eggs lack an operculum. The unmistakable posterior spine thus points to Schistosoma haematobium when examining urine specimens.