Case of the Week 620

This week's case is a nice straight-forward one because - spoiler alert - we are going to have a really fun challenge from Idzi Potters next week to start off our new year. 

The following worm was found during routine colonoscopy. Identification? For 'extra credit' - which end is anterior? And is this a male or female?

Answer to Case 620

 Answer to Parasite Case of the Week 620: Trichuris trichiura, a.k.a. "whipworm". This is a male, as evidenced by its curled tail and copulatory spicule (note the location of the anterior and posterior ends):

Be sure to check out the comments section to see all of the creative comments that go with this case!

Case of the Week 619

 Dear readers,

Wishing you and your family a very happy, safe and healthy holidays. To celebrate the season, I thought I would share a few of my favorite photographs from my 2020 calendar - all decked out for the holidays. Can you tell what they are?

Answer to Case 619

Answers to Parasite Case of the Week 619: Trichuris trichiura, Schistosoma couple, and Hymenolepis nana.

Case of the Week 618

 This week's case features some photos from a cool histopathology case I found in my archives. The source is "large single liver cyst". Identification? What cool things do you see in these images?

Answer to Case 618

 Answer to Parasite Case of the Week 618: Echinococcus granulosus sensu lato species complex

There are many cool features in this cool case. Here are just a few that I thought were worth pointing out:

First, note how you can see a portion of all of the layers of the cyst. Going from the outside-inward, you can see the compressed host tissue, outer most parasite-derived layer (laminated layer), the granular layer, and several brood capsules, each containing multiple protoscoleces.

Within the individual brood capsules are many inverted protoscoleces arising from the granular layer. We even managed to get a section showing how one protoscolex is attached to the cyst granular layer by a thin stalk. Numerous, variably-sized, calcareous corpuscles are also seen: 

Another cool feature in this case is the presence of degenerating protoscoleces within some of the daughter cysts, resulting in freed hooklets. The resultant gritty fluid is referred to as hydatid sand. 

Protoscoleces don't usually evert unless they have been ingested by the definitive canid host. They then mature into the adult worm and live in the gut of the host. I'm guessing that eversion occurred in this case as part of the degenerative process.

Thank you for all of the comments!

Case of the Week 617

 Here is our monthly case from Idzi Potters and the Institute of Tropical Medicine, Antwerp. The following were seen in a stool specimens in a patient with diarrhea and recent travel to sub-Saharan Africa. 

Unstained wet mount: 

Combined iron hematoxylin-Kinyoun stain:

Identification?

Answer to Case 617

 Answer to Parasite Case of the Week 617: Cystoisospora (formerly Isospora) belli

The diagnostic features in this case include the size of the oocyst (~25 micrometers), oval shape, internal structure (single sporoblast in the wet prep) and acid fast positivity on the iron hematoxylin Kinyoun stain.  The acid fast positivity allows us to rule-out Sarcocystis sp. as the oocysts of this parasite are not acid fast. 

Kamran and Florida Fan noted that the oocysts of C. belli autofluoresce beautifully when examined with an excitation filter of 330 to 365 nm. As Blaine will tell us, they also exhibit a less intense fluorescence when examined with an excitation filter of 450-490 nm. Here is a great example of this autofluorescence from Florida Fan:

Note that this oocyst from Florida Fan has 2 sporoblasts, which is unusual to see in freshly passed stool specimens. Most C. belli oocysts are shed in an immature state - either unsporulated or partially sporulated (with only one sporoblast). They mature further in the environment, with the sporoblast dividing in two so that the mature oocyst has 2 sporoblasts. The sporoblasts become sporocysts with a surrounding cyst wall, and the sporocysts divide twice so that they produce 4 sporozoites each. Here are some great photos from Idzi showing this (you can see the sporozoites in the last image):