Answer to Case 664

Answer to the Parasite Case of the Week 664: Hymenolepis (Rodentolepis) nana scolex and egg.

It is very unusual to see a scolex of H. nana; in my experience, it is usually only the proglottids that are removed when seen during colonoscopy. Therefore, it's a real treat to get to see the scolex in an actual clinical specimen! 

Like Taenia solium and Dipylidium caninum, the scolex has an armed rostellum (i.e., protrusion with hooklets). The rostellum of H. nana is generally smaller than that of T. solium, and is often retracted. 

The presence of characteristic H. nana eggs allows for definitive identification. Note the filaments emanating from each pole of the inner membrane.

Answer to Case 762

Answer to the Parasite Case of the Week 762: Enterobius vermicularis male

As noted by Idzi Potters, "The ribbed cephalic alae are typical for an Enterobius vermicularis adult. The curved tail and spicula (although retracted) point towards an adult male." These features can be easily appreciated in the below composite image. Thanks again to Felicity for the beautiful photographs!

Thanks also to all of those who wrote on Facebook, X (formerly Twitter), and LinkedIn with questions and comments. Some were intrigued that this worm was found on routine screening colonoscopy, which prompted me to count up the number of cases on my blog that had been discovered in this manner. It turns out that we multiple examples of adult nematodes and cestodes featured, including Trichuris trichiura (Cases 73, 155, 306, 362, 405, 448, 490, 515, 598, and 631), hookworm/Ancylostoma duodenale (Cases 520 and 759), Taenia saginata (Case 353), Rodentolepis (Hymenolepis) nana (Cases 756, 664, and 169), and Dipylidium caninum (Case 378). We also had a previous male E. vermicularis on this blog detected during screening colonoscopy (Case 576). I wasn't aware that I had accumulated so many of these incidental cases over the years! 

Others asked about the clinical significance of this finding. In this case, the patient was asymptomatic and there was likely no clinical relevance. This is not surprising, as enterobiasis is frequently asymptomatic,. However, it is likely that this patient was treated to eliminate the chance of him serving as a reservoir for infection.

Case of the Week 664

 Here's another fun case from my lab, courtesy of our awesome parasitology technical specialist, Heather Morris. The following objects were found on screening colonoscopy.

The following helpful object was found in the accompanying fluid:

Identification?