Case of the Week 330

This week's case was generously donated by Dr. LoAnn Peterson and Dr. Alicia Franken from Northwestern Memorial Hospital in Chicago.  The patient is a male in his early 50s with recent travel from Cameroon.  The following images are from Wright-Giemsa stained thin films made from peripheral blood.  Identification?

Answer to Case 330

Answer:  Plasmodium falciparum, heavy parasitemia

This case shows several of the characteristic morphologic features of P. falciparum infection, including normal size of the infected RBCs, the presence of only delicate ring forms (early trophozoites), and specialized "applique" and "head phone" forms.  There are also multiply-infected RBCs, which is characteristic (but not definitive) for P. falciparum. No stippling is present.  As noted by several readers, this is a heavy infection.  Calculation of percent parasitemia is important for guiding therapy and predicting patient prognosis. Note the presence of malaria pigment (hemozoin) inside of the neutrophils in the second image):

An important feature pointed out by Florida Fan is that a few of the RBCs are crenated, which should not be mistaken for the "fimbriations" of P. ovale.  Some clues that can help in this regard are that the infected RBCs are not enlarged (as would be expected for P. ovale - particularly in later stages) and that crenation is seen both infected and non-infected cells.  The latter is probably the most important point, since this indicates that crenation effect is due to either host factors or, more likely, an artifact of smear preparation, and not due to the presence of the parasite inside the RBCs.

Case of the Week 329

Happy Holidays to all of my Readers!

Here is a special holiday poem from Blaine Mathison:

You better not cheat

You better not stray

You better be careful

with whom you play

Santa Crab is coming to town.

He’s causing an itch

making you scratch

with those strong raptorial claws

hard to get him to detach

Santa Crab is coming to town.

He loves it when you’re sleeping

for that’s when he becomes aroused

You can buy up all the permethrin in town

you’ll still have to explain it to your spouse.

O! You better not cheat

You better not stray

You better be careful

with whom you play

Santa Crab is coming to town.

New Parasitology Bench guide

Dear Readers,
You may be interested in a new Parasitology bench guide that I produced through the College of American Pathologists Press: (shameless promotion, but I make no money from this book)

I'm pleased with how the bench guide turned out and think it will be useful for general reference at the bench or for boards preparation.  Here's a sample image from the benchguide:

Answer to Case 329

Answer:  Santa Crab, a.k.a. Pthirus pubis, the crab louse, characterized by its triangular short body and raptorial (crab-like) claws.

Happy Holidays to all of my readers!

Case of the Week 328

The following were seen in Giemsa-stained peripheral blood films from an Indonesian man.  Identification?

Answer to Case 328

Answer:  Brugia malayi

Thanks to everyone who wrote in - you all got this one right.  Shown are clearly sheathed microfilariae with a clear space between the terminal and subterminal tail nuclei (arrows below).  The deep pink color of the sheath is strongly supportive of B. malayi, although sometimes the sheath can be clear. 

A couple of my former students recalled my favorite ways for differentiating the sheathed microfilariae (thank you Trish and Neal).  The 3 sheathed microfilariae can be remembered by the phrase Wears Long Britches (W-Wuchereria, L-Loa loa, and B-Brugia).  I think of the sheath as a long pant leg (britches or breeches for my English friends).  

When a sheath is identified, then the 3 genera can be differentiated by the characteristics of their tail nuclei.  The tail of Wuchereria bancrofti is Without nuclei, the tail of Brugia is Bi-nucleated (or makes a ba-dump-a-dump pattern, a phrase courtesy of Heather), and finally, the nuclei of Loa loa "flowa flowa" to the tip of the tail.  

Everyone has their own preferred way of learning things, so if these silly tips and tricks don't help you, feel free to disregard!

Case of the Week 327

Happy Thanksgiving to all of my readers in the United States!  In appreciation for this day of celebration (which usually involves the sharing of delicious food with family and friends), I've decided to have a food-based case, which doesn't technically involve a parasite, but rather the relative of some human parasites.

The following is a French hard cheese that has been aged for 1 year.  It is known for its deep orange color and rough rind which both make it resemble a cantaloupe.

Close up of the rind:

By scraping the rind and placing the scrapings, along with a drop of saline, on a glass slide, you see the following:

Identification of these arthropods?
(I hope this doesn't turn anyone off of cheese!)

Answer to Case 327

Answer:  Cheese mites!  Specifically Acarus siro, the mites used to create the very distinctive crust and taste of this French cheese called Mimolette.  Mimolette cheese is colored with annatto to provide its cantaloupe" orange color, while the mites are intentionally introduced to the external surface to provide its gray crust.  The mites are thought to add to this cheese's distinctive parmesan-like flavor.

Despite some over-hyped media reports, the Food and Drug Administration has not actually banned the importation of Mimolette cheese into the United States.  However, there have been reports of halted shipments at the border due to failure of the cheese to meet regulations due to excess of mites on the cheese.  I couldn't find any reference to this on the FDA's web page, but here is a good report from National Public Radio.

Case of the Week 326

Here is another great case from Dr. Orihel's collection at Tulane University.  No history, but the appearance is quite classic. Identification?

Answer to Case 326

Answer:  Taenia sp. larvae, otherwise referred to as cysticercae (cysticercus = singular).  If these were found in a human, then they would be cysticercae of T. solium, which are commonly referred to as Cysticercus cellulosae. Thank you to everyone who wrote in with the answer.  As noted by Florida Fan, you can see a similar image in Ash and Orihel's Atlas of Human Parasitology, 5th edition, on page 371.

Cysticercae have a characteristic solid structure (the inverted scolex) surrounded by a fluid filled cavity called a bladder.  For this reason, Taenia solium is sometimes referred to as the bladder worm (although I would discourage using this terminology since it is confusing to most people).

Remember that a 'bladder' is simply a fluid-filled or air-filled sac and doesn't just refer to the urinary bladder.  Other well-known bladders are the gallbladder and the fish swim bladder .

Case of the Week 325

Dear Readers,
For this post, I wanted to highlight one of the fabulous cases from Tulane University, the former lab of the Parasite guru, Thomas Orihel.  I had the pleasure of putting on a Parasitology workshop last week at the ASTMH annual meeting along with Christina Coyle, Michael Libman, and Susan McLellan; Susan is an infectious disease physician at Tulane and was our host for the workshop.

The following is one of the coolest displays I've ever seen - back from the 1950s when tapeworms were submitted following treatment (often with quinacrine) to ensure that the head was expelled. On an interesting historical note, quinacrine is not thought to have vermicidal activity, but causes the head to detach so that the worm can be expelled.  Its use has now been replaced by praziquantel and other more effective medications for treatment of cestode infection.

Identification?

Answer to Case 325

Answer:  Taenia saginata: intact long segment of attached proglottids wrapped around a glass rod and carefully preserved inside of a cylindrical tube at Tulane University.

Given that the proglottids are longer than wide and quite large, it is easy place this into the Taenia genus.  However, if you look carefully, you can also tell that the proglottids have been cleared so that the uterine branching pattern is visible; there are 15 or more primary uterine branches along one side of each proglottid consistent with T. saginata. What a beautiful display!

If you haven't already, please read the very poignant story that Florida Fan tells about his own experience with tapeworm infection.  It is in the comments from this case (question section).  

Case of the Week 324

The following large structures were seen on a stool wet mount preparation, measuring from 50 to 80 micrometers in largest dimension. The patient has a history of chronic intermittent diarrhea that is occasionally bloody and abdominal pain.  Identification?

Answer to Case 324

Answer:  Balantidium coli

As noted by Florida Fan, the cilia, macronucleus and cytosome (mouthparts) are plainly visible in the photos of the trophozoite (below, first image) while the macronucleus is partly visible in the cyst (below, bottom image).

As noted by Anon, the classic motility of the ciliated parasite is described as "boring" - not "uninteresting" but "rotary"!

Thank you to everyone who wrote in with the answer.

Case of the Week 323

Happy Halloween to all my readers!  This week's case will be a be a bit unusual.  I had my annual Halloween party last night and had a great turn out from my lab and our pathology and microbiology trainees.  Here are some of the top parasitology costumes.  Can you guess their identity?

Below is a different take on the same costume as above.  Any thoughts on what the fellows are? 

I also made some special 'myiasis' cupcakes for the party.  Here is the assembly process and the final product:

Rolled fondant with red sugar sprinkles

Fondant 'maggots'

 Assembled cupcakes containing a 'maggot' in a custard 'pus' center.  The fondant is held onto the cupcake by a layer of buttercream frosting:

Removing the maggot reveals almost too realistic custard 'pus'

The cupcake idea was not my own, alas.  I got the idea from this web site.

Answer to Case 323

Thank you readers for giving your best guess for what my lab staff and trainees were for Halloween!  Here are the answers:

Mommy Taenia solium and her 3 motile proglottids. Note Jaydee's hooked rostellum, 4 suckers and proglottids of increasing length (arrows).  

As an interesting coincidence, these 2 ladies also came as T. solium with accompanying eosinophils for their dates.  Each have 3 proglottids in their costume.  Near the end of my 'wild' parasite party, the eosinophils degranulated and the parasites had to fend for themselves.

My lead tech and parasite queen extraordinaire came as a D. caninum egg packet containing ova with appropriately hooked onchopheres.

We also had a little parasite who couldn't make it to the party but was too cute to leave out:  a little Dermatobia hominis

 

Case of the Week 322

The following case was donated by Dr. Tess Karre.  This was an incidental finding in sections of duodenum that had been removed during a gastric restrictive procedure from a 50 year old morbidly obese patient.  There was no travel history outside of the United States.

Identification?

Answer to Case 322

Answer:  Cross-sections of Enterobius vermicularis adults in the duodenum.  Although this is an unusual location for this worm, the characteristic lateral alae and features of an adult worm (internal organs including intestine and testes) allow us to make the diagnosis.  E. vermicularis is the only adult worm found in humans that has lateral alae (although various larvae may also have lateral alae).

From Blaine Mathison:

While the duodenum is an unusual place to find this worm,

the morphologic features shouldn't cause you to squirm

With lateral alae pointing to the sides

and platymyarian musculature low and wide

a diagnosis of pinworm should be relatively firm!