Sunday, November 28, 2010

Answer to Case 141

Identification: Schistosoma japonicum ova

The key to making the identification is recognizing the overall shape and size (oval non-operculate eggs that are too large to be hookworm), lack of internal hooklets (as would be seen in Hymenolepis nana and H. diminuta, and finally, the presence of a small, but distinct lateral rudimentary knob, as shown here:

A rudimentary spine is not always visible on S. japonicum eggs, but the other features (size, shape, lack of hooklets) will still allow for a presumptive diagnosis.

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