Case of the Week 782

This week's case was generously donated by Dr. Adrienne Showler. The following image is from a video capsule endoscopy performed on an immunocompromised patient with diarrhea. The patient has not travelled outside of the US and has no other risk factors for parasitic infection. Numerous of these objects were seen - none were moving. Identification?

Case of the Week 781

This week's case features a beautiful video from Dr. Rasool Jafari. The specimen is skin scrapings. What is your identification?

Answer to Case 781

 Answer to Parasite Case of the Week 781: Demodex sp.  The legs and gnathosoma (with mouthparts) are nicely demonstrated:

I can't quite tell if this is D. brevis, or Demodex folliculorum with a scrunched-up tail. 

We've had some great cases of Demodex on the blog over the years. Here is the list in no particular order:

Case of the Week 535 (with a poem from Blaine Mathison 😁), donated by Dr. Kabeer Shah.

Case 581 - showing an adult D. folliculorum and a video of 2 mites within a hair follicle. Also with a poem by Old One. This case was donated by Theodore Trejo and shows beautiful detail of the adult mite.

Case 702 - from the Mayo Clinic Mycology lab showing D. brevis on calcofluor white fluorescent stain.

Cases 278 - showing a pair of mites on calcofluor white fluorescent staining - with another poem from Blaine! I hadn't realized how many poems we have collected. This case was donated by Florida Fan.

Case 606 - donated by Dr. Sandeep T and showing a lovely long D. folliculorum.

Case 772 - This is the tricky case from last month with the twisted tail. Donated by Dr. Evis Nushi.

Case 503 - from Florida Fan with a really nice side-by-side view on light and fluorescence microscopy.

Case 334 - showing several D. folliculorum mites from eyelash scrapings. Donated by Dr. Robin Chamberland - with yet another poem by Blaine. All of the poems are different from one another, and very fun to read. 

Case 58 - the very first Demodex that I ever posted - 16 years ago!

Case 190 - a beautiful example of D. folliculorum in a hair follicle in an H&E-stained histopathology preparation. It was donated by Dr. Holkmann Olsen and is the best example I've ever seen of the mouthparts and legs in a histopathological section. 

Case 308 - and finally, an amazing case by Florida Fan that shows Sarcoptes scabei and Demodex folliculorum mites in the same image. 

I've been blessed to have so many fabulous case donations over the years. Many thanks to Dr. Rasool Jafari for donating this fascinating case.

Case of the Week 780

This week's case was generously donated by Dr. Manohar Mutnal. The following were seen in a peripheral blood smear from a patient with an unknown travel history. What is your differential diagnosis? What additional information would you like?

Answer to Case 780

Answer to Parasite Case of the Week 780: Trypanosoma brucei trypomastigotes. 

As noted by Florida Fan, "This is definitely a case of trypanosomiasis. The flagellate doesn’t show a prominent kinetoplast nor assume a C shape in general. This rules out Chagas disease caused by T. cruzi. We have Trypanosoma brucei, yet morphology alone doesn’t warrant a differential diagnosis of subspecies gambiense nor rhodesiense." 

Idzi also noted that "In the first picture we can clearly see the difference between the two morphologies of T. brucei: the "short stumpy" form (adapted for survival in the tsetse fly vector --> transmission) versus the "long slender" form (which multiplies in the host)!" Here is an annotated version of this image showing these two morphologies:

I had also asked what additional information is needed in this case - and you all responded with excellent suggestions. In summary,  

• We first, we need to know the travel history to determine the likely subspecies. PCR could also be performed. This is important for treatment and prognostic implications. 
• Second, we need to know the stage of disease, as this will also drive treatment decisions. As noted by Idzi, "A lumbar puncture will be able to tell us if the patient has evolved to stage II of the disease, where the parasite has invaded the central nervous system. Even if no tryps are found in the CSF, a raised number of WBCs in the CSF will still be indicative of stage II disease (when tryps are found in the blood).

The WHO released updated treatment guidelines for Human African Trypanosomiasis (HAT). Treatment is complex and can have significant side effects. This is especially true for rhodesiense-HAT, in which intravenous suramin is used for first stage disease and melarsoprol, an arsenic derivate, is used for second stages disease. It's shocking that we are still using arsenic to treat infectious diseases. Melarsoprol has many adverse effects, including reactive encephalopathy which has a 3–10% fatality rate!

Getting back to this case: additional history revealed that the patient had been on a hunting trip to Zambia, and therefore we can infer that the patient has East African HAT caused by T. b. rhodesiense. Idzi predicted this, stating that "chances are very very big that this is T. b. rhodesiense because this is the subspecies that will get quickly to a parasitemia high enough to be able to detect the trypanosomes in a thin blood film." 

Many thanks again to Dr. Mutnal for donating this interesting case. 

Case of the Week 779

This week's case was generously donated by Dr. Richard Bradbury. A patient living in The Gambia presented with high fever, body aches, and altered consciousness. Images from the Giemsa-stained thick and thin blood films are shown below. 

Due to a shortage of coartem, quinine was administered. Shortly afterwards, the patient's urine turned dark brown:

What is this condition, and what is it caused by?

Answer to Case 779

Answer to the Parasite Case of the Week 779: "Black Water fever" - a massive hemolytic event associated with P. falciparum infection and quinine administration. 

Black water fever was previously an important cause of death and was prominently reported in British soldiers in the early 20th century. Thankfully, it is rarely seen today with the advent of synthetic antimalarials (e.g., chloroquine) and artemisinin combination therapies. The exact etiology is poorly understood, and seems to be attributed to a complex interaction between the host RBC, the parasite, and antimalarial drugs. It may also occur more often in people with G6PD deficiency.

Case of the Week 778

This week's case features the intestinal biopsy of a middle aged man with abdominal pain and diarrhea. The astute pathologist noted these small objects (~20 microns in greatest dimension) associated with ulcerated colonic mucosa. Stain is hematoxylin and eosin (10x, 40x, and 100x objectives). What is your diagnosis? 

Answer to Case 778

Answer to the Parasite Case of the Week 778: Amebiasis due to Entamoeba histolytica. 

As noted by Dr. Jacob Rattin, "It looks like there is ulceration in the adjacent mucosa and Entamoeba histolytica trophozoites with visibly ingested red blood cells." Several others also noted the ingested RBCs within the trophozoite cytoplasm. 

When seen in stool specimens, the presence of RBCs within Entamoeba trophozoites allows us to presumptively call this E. histolytica rather than one of the identical-appearing amebae such as E. dispar. However, in this case, we have another important clue that allows us to presumptively identify the ameba, even if we don't see ingested RBCs: the presence of trophozoites associated with or invading into the ulcerated mucosa. E. dispar is not considered a pathogen, and other doppelgangers (e.g., E. moshkovskii, E. bangladeshi) have not been definitively shown to be pathogenic. Thus, the presence of invasive Entamoeba trophozoites points us towards E. histolytica. Note that the trophozoites look somewhat different in tissue than they do in stool as the central chromatin dot is often not present. However, the outer rim of chromatin is easily visible. 

Case of the Week 777

 Dear Readers,

I am excited to announce that we are celebrating our 777th case! 

In honor of this milestone, we have a selection of 3 helminth eggs for you to identify. You win the parasite jackpot if you can get all three. There is an 'easy' and 'hard' version, so you get to take your pick.

EASY VERSION

Egg 1 (50 micrometers long)

Egg 2 (55 micrometers long)

Egg 3 (35 micrometers long)

HARD VERSION

Egg 1 (45 micrometers in diameter)

Egg 2 (95 micrometers long)

Egg 3 (One of 15 objects freed from a 4mm structure)