Wednesday, September 30, 2020

Case of the Week 608

 This week's case is from Dr. Peter Gilligan. It's a histopathology image - which I know isn't always popular with the classical parasitologists! But I think you might be able to take a stab at the diagnosis regardless. The following eggs were seen in an ulcerated area of an intestinal biopsy. They measure approximately 30 micrometers in diameter. Identification?

Tuesday, September 29, 2020

Answer to Case 608

 Answer to the Parasite Case of the Week 608: Taenia sp. egg. The eggs are those of T. solium, T. saginata, or T. asiatica, but it is not possible to tell the species from the egg alone. You can find more informations about these interesting cestodes on the CDC's DPDx website.

Note the classic small size (30-35 micrometers in diameter) of the eggs. Each have a thick radially-striated outer wall and internal 6-hooked oncosphere. 

The hooks aren't easily visible with H&E, but they are refractile when viewed with a narrowed condenser. It is likely that the eggs were released from a mature gravid proglottid in the large intestine and made their way into an ulcerated region of the mucosa where they were an incidental finding on biopsy. Taenia solium and T. saginata do not invade the mucosa (other than at the point where the hooklets anchor the adult worm's scolex to the small intestine), so there must have been some other condition present that caused the intestinal disruption in this patient.

Some readers commented that this could also be Echinococcus sp. if this was a canid rather than a human host. Echinococcus spp. adults are found within the canid definitive host and the eggs are shed into the environment where they are ingested by herbivore intermediate hosts. Humans are accidental intermediate hosts. After ingesting the eggs from the environment, the eggs hatch in the small intestine to release the oncosphere. Thus we wouldn't expect to see intact Echinococcus sp. eggs in humans. The oncospheres penetrate the wall of the human host and enter the circulatory system to travel to the organs (usually the liver) and form the cystic form of the parasite.

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

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