Answer to Case 539

Answer to Parasite Case of the Week 539: Hymenolepis nana

This beautiful egg donated by Florida Fan nicely demonstrates all of the classic features of H. nana, including the thin inner membrane surrounding the hooked oncosphere [*] from which polar filaments arise. The polar filaments arise from opposite poles of the inner membrane (arrows) and spread out into the space between the inner and outer membranes, thus providing a key differentiating feature from the filamentless-Hymenolepis diminuta.

Blaine wrote a poem for this parasite back when I featured it in 2013. Here it is again for your enjoyment:

There once was a kid from Indiana

Who with his oatmeal did like banana

But with his food he did eat

A most wonderful treat

The cestode known as Hymenolepis nana

If you google "oatmeal" and "bugs," you will find multiple consumer complaints (and some nice YouTube videos) to explain the oatmeal reference!