Monday, September 21, 2020

Case of the Week 607

 This week's case was donated by my colleague, Dr. Tom Grys. Tom and I did our Clinical Microbiology fellowship together and had a lot of fun! 

The following specimen was brought in by a patient after finding it near his eye upon wakening. He is concerned that it might be an ectoparasite or vector of human pathogens, and is hoping that the laboratory can provide this information. What is your identification, and how would you counsel the patient or patient's clinician?

Sunday, September 20, 2020

Answer to Case 607

 Answer to Parasite Case of the Week 607: Beetle, not a human parasite. 

While I am not an entomologist, I fortunately have many readers who are. Blaine Mathison commented that this is likely a sap beetle in the family Nitidulidae. This was also supported by Dr. Kosta Mumcuoglu and his entomologist colleague, Mr. Ariel-Leib Friedman, MSc, who is the Coleoptera Collection Manager at The Steinhardt Museum of Natural History, Tel Aviv University, Israel. Kosta said "I am not sure about the genus, but Carpophilus and Epuraea are most commonly associated with human surroundings and are considered minor agricultural and store pests." Josh, Blaine and Joshua Place also felt that this might be a carpophilus beetle. Joshua notes that none of these beetles are ectoparasites or vectors of humans disease. 

This is good news to the patient and provider, who can both be reassured that the presence of this arthropod does not represent parasitism, or a medical risk. However, it might indicate to the patient that it's time to clean up the pantry and secure windows and doors to keep further bugs out!

Monday, September 14, 2020

Case of the Week 606

 This week's case is from Sandeep T, the same individual who contributed the amazing Case 409 from many years past. The current case is less dramatic, but a beautiful example of a classic. The following were seen on skin scrapings from a young man with a 2-month history of severe itching in the back of his left ear. The physician suspected fungal infection and ordered a KOH wet mount of the skin scrapings. This is what was seen. Identification?

Sunday, September 13, 2020

Answer to Case 606

 Answer to Parasite Case of the Week 606: Demodex folliculorum, the human follicle mite. Like all mites, this arthropod is an arachnid, related to ticks and spiders. It is NOT an insect. Note the presence of 8 legs in its adult state.

If you have time and interest, I would encourage you to check out the comments from other readers. Florida Fan reminded us how beautiful these mites look when using the Calcofluor KOH stain with UV light excitation (See Case of the Week 278 to see lovely little pair of mites), and Dr. Pankaj commented that the mites stain red with an acid fast stain. I will definitely have to try this! 

I also like Kosta's suggestion of having students sample their ears for Demodex mites. Another thing I will have to try. After all, part of the fun of teaching parasitology is 'grossing everyone out'. Also, as Idzi mentioned, it is a great reminder that one is never along, along as the Demodex buddies are there!

Monday, September 7, 2020

Case of the Week 605

 Happy Labor Day weekend to all of my American readers! I hope you are having a restful and safe holiday weekend. It's the first Monday of the month and time for our case from Idzi Potters and the Institute of Tropical Medicine, Antwerp. A middle-aged man brought the following worm to his primary care provider. He noticed it in the toilet after a bowel movement. Identification?

Sunday, September 6, 2020

Answer to Case 605

 Answer to Parasite Case of the Week 605: Earthworm, an oligochaete. As a segmented annelid, these worms usually have a few setae (i.e., bristles) on their outer body surface, as seen in this case, which aid in their identification, and differentiation from large parasitic worms such as Ascaris lumbricoides.

As so nicely stated by Florida Fan, "Did we say “after the bowel movement”? Good thing the patient did not pass it out. Yes, we have seen this annelid a few times. (See Case 545, Case 344, and Case 234). It always shows the locomotive spicules on each ring of the body. A diligent, hardworking creature, it bores it tunnels through the rich loam most often ignored by most, it aerates its living Earth. Gardeners prize it for its urine and pellets, fisherman love it as their succulent wiggling bait irresistible to passing fish. Yet the humble night crawler got its place in French poetry in the poem “Le lombric’’. One time, I was formally complained to the medical director for signing the report as ‘’earth worm’’, the sample was referred to the State Laboratory where it was confirmed as being a Lumbricus terrestris. Yes this harmless worm can give a panic to a few caring parents. Well, long story short I should stop before being reprimanded for being ‘’Le Grand Bavard’’."

Don't worry Florida Fan - we will not accuse you of being a big talker, as we greatly appreciate your stories and descriptions!

Now to answer the question that one reader raised on Twitter - how did it get into the toilet? My plumber friend tells me that tree roots are the enemy of household pipes. Over time, the roots grow into pipes, leading to cracks and fissures through which our earth-living friends can enter. The video in this case can show how earthworms can be vigorous swimmers. They can easily swim 'upstream' to enter our toilets, and then be mistaken as a parasite of concern. 

So let's end with some levity, starting with the wonderful age-old joke from Old One:

 Florida Fan: "Hey Old One are you going fishing?". 

Old One: " Yeh". 

Florida Fan: " Got worms?" 

Old One: " Yeh, but I'm going fishing anyway."

And a poem from Blaine Mathison:

To see a worm wiggling in a toilet bowl

would certainly on anyone take its toll

but there's nothing to fear

for it didn't come out your rear

but a crack in your pipes allowed contamination from the soil!

For those of you who would like a more serious poem (with no offense to Blaine's), Florida Fan and Sir Galahad remind us of the poem by Jacques Roubaud, "Le lombric" (the Earthworm). You can find a passable translation HERE


Monday, August 31, 2020

Case of the Week 604

 This week's case was generously donated by Dr. Peter Gilligan, and features a histopathology section of an appendix from a patient with Crohn's disease. The pathologist was concerned when they saw the following object in the lumen of the appendix. Identification?

Sunday, August 30, 2020

Answer to Case 604

 Answer to Parasite Case of the Week 604: Plant material, not a parasite. Although the large size and round shape in section superficially resembles a cross-section of a large roundworm (i.e., Ascaris lumbricoides), there are some key features that allow us to identify this as plant material. 

As nicely stated by Florida Fan, "There does not seem to be a layer of polymyarian muscle cells as well as the other anatomical components such as a digestive tube or reproductive organs and no excretory organs either" which would be seen in Ascaris lumbricoides. He also adds: "when magnified enough we can see polygonal cells often observed on vegetable matters. The other observation is that there is a fine brown line inside which I believe to contain melanin pigment, a character we do not find in helminths."

These are excellent observations on the key features for distinguishing plant material - in this, likely a cereal bran - from round worms. The polygonal cells are a characteristic feature of plants, and can be seen in the outer layer of the structure in this case

This outer layer would likely have been birefringent with polarized light, which is another helpful feature for differentiating plant material from helminth body layers. Dr. Mary Parker, a botanist, kindly provided the following explanation for this case:  "I am pretty sure this is plant material, probably a few layers of the bran of a cereal grain. One of the layers of cereal bran contains a water-insoluble orange/red pigment called phlobaphene which give the grain its colour. This pigment layer is most obvious at 5, 8, and 12 o'clock on your section image. Botanists call a cereal grain a caryopsis because it is technically a seed with the fruit wall adhering to the outside (I explain this to my students as one pea in a pod with the pod adhering to the pea surface). Cereal bran therefore consists of layers derived from the fruit wall and the seed testa, and it is one of the testa layers that is pigmented. The digestive process does separate these layers." 

For comparison, here is a cross-section of A. lumbricoides, showing the thick acellular outer cuticle, underlying hypodermis, and tall polymyrian muscle cells. Note also the sections of internal organs.


Thanks again to Dr. Gilligan for donating this interesting case!

Tuesday, August 18, 2020

Case of the Week 603

 Here's a fun case for us this week from my technical specialist, Emily Fernholz. The following objects were seen on a Giemsa-stained thick film from a patient with recent travel to the Western United States. Diagnosis? What additional testing would you recommend?

Sunday, August 16, 2020

Answer to Case 603

Answer to Case of the Week 603: Borrelia sp. spirochetes. The history is most consistent with a relapsing fever Borrelia sp., and subsequent PCR showed this to be Borrelia hermsii

As Florida Fan mentioned, this case is a great reminder that when we examine a Giemsa-stained blood film, we may find things other than parasites. In addition to spirochetal bacteria such as in this case, we can find intracellular clusters (morulae) of Anaplasma phagocytophilum and Ehrlichica spp. bacteria, and intracellular years (e.g. Histoplasma capsulatum, Talaromyces marneffei). Leishmania spp. amastigotes can also rarely be seen within phagocytic cells. I've shown Borrelia spirochetes on this blog before (see Case of the Week 502), but never on a thick film, so I thought this would be a nice case to include here.

Note that the spirochetes are uniformly slender with broad undulations. This is different than the microgametes of an exflaggelated Plasmodium sp. microgametocyte which I previously showed on Parasite Case of the Week 595. In that case, I created a composite image of 'squiggly things' seen on a blood smear which may be helpful in identifying and differentiating them:

Some readers asked if the Borrelia species that cause Lyme disease could also be seen on blood film. The answer to this is NO - with one small caveat. The main cause of Lyme in the United States and Canada is Borrelia burgdorferi, whereas in Europe, you can also see B. garinii and B. afzelii. These organisms have extremely low levels of spirochetemia, and therefore spirochetes are NOT seen on peripheral blood films. The only rare exception to this is Borrelia mayonii, an uncommon cause of Lyme disease restricted to the upper Midwestern United States. This organism is actually found in much higher concentrations in the blood, and occasionally a rare spirochete can be seen on peripheral blood smears. We published on this several years ago; you can read the article HERE. (Let me know if you would like a copy).

There were many other good comments posted on this blog case - both in the Comments section and on Twitter - so I would encourage you to read them to learn more about the experiences from our readers.