Monday, December 9, 2019

Case of the Week 572

This week's cool case is from Dr. Marta Maia. The specimen is skin currettings, and the object below was viewed using a dissecting microscope. The patient had developed a firm, painful 3 mm-diameter lesion on the sole of his foot after a recent vacation in Brazil. During his vacation, we swam in the ocean and walked barefoot on the beach. Identification?

Monday, December 2, 2019

Case of the Week 571

Welcome to the first case of the month, a regular feature by Idzi Potters and the Institute of Tropical Medicine, Antwerp. The following objects were seen in an unstained duodenal aspirate specimen. Identification?





Sunday, December 1, 2019

Answer to Case 571

Answer: Giardia duodenalis (a.k.a. G. lamblia, G. intestinalis) trophozoites with "falling leaf" or "tumbling" motility. Note that this is quite different than the "spiraling" motility of Chilomastix mesnili and the "jerky" motility of Pentatrichomonas hominis - two other flagellates - both non-pathogns - that may be seen in human stool specimens. As pointed out by Florida Fan, the motility is further enhanced by dark field videography, which makes everything more interesting. Thanks again to Idzi for the very cool videos!

Santiago gave us further information on how Giardia trophozoites move in the intestine to attach to the duodenal intestinal mucosa:
After excystation in the small intestine, the trophozoites quickly swim towards the epithelium and attach forming a monolayer; this contributes to the pathology and allows the parasite to escape the turbulent flow of the small intestine and continue the life cycle in the human host.
To achieve this, it uses a combination of movements involving its four pairs of flagella as well as its caudal region, and it is able to switch its motility from "free swimming" in the intestinal lumen, which is more rapid, to a "pre-attachment" pace which is slower and more stable, facilitating effective attachment to the intestinal epithelium in the desired location to form a monolayer.

Lastly, Old One reminds us how
Antonie van Leeuwenhoek was delighted when he took a look
at his own watery stool
Seeing For the very first time
Animalcules

“Bellies flatlike with bodies furnisht with sundry little paws. making quick motion with these paws, yet for all that, they made but slow progress yet a-moving very prettily.”

What a neat parasite!

Monday, November 25, 2019

Case of the Week 570

This week's case was generously donated by Dave Neitzel at the Minnesota Department of Health. A mutant headless tick! Wouldn't it be great if they were all this way?

Can anyone identify the genus of this tick?

Sunday, November 24, 2019

Answer to Case 570

Answer to Parasite Case of the Week 570: Ixodes scapularis adult female with a missing external capitulum and mouthparts. Or as Blaine noted, "A headless tick:  Ichabod scapularis!"

The image below shows these parts where they are normally located on the accompanying female tick (white oval):
Examination of the ventral aspect shows an "inverted-U" shaped anal groove, allowing this tick to be identified to the Ixodes genus. One reader had queried if the genital pore was also absent on our mutant tick, but re-examination by Dave Neitzel indicated that it IS there; it is just obscured by the glare of the light.

So how did this happen? Well, Dave and some of our readers rightly indicated that the tick must have taken 2 prior blood meals in order to molt from larva to nymph, and then nymph to adult; thus it must have had functional mouthparts during those previous stages. However, as Dave noted, "something went horribly wrong during the last mold from nymph to adult. Given the radical changes that occur during a molt, I am surprised that we don't see more obvious mutations!" He also shared that he has seen several 7-legged ticks from his regular field collections in Minnesota, but surprisingly, no other mutants. He hypothesized that the capitulum and mouthparts are still present, but that they are inverted and therefore not externally-facing. The lack of of the visible capitulum and mouthparts has shifted the position of the legs, thus making them look longer. Finally, he commented on the "sclerotic structure" noted between the first pair of the legs by Makrone.  He also had seen this and speculated that it might be some of the residual tissue from the inverted mouthparts/capitulum.

Thanks to Dave for the fascinating case! As Sam mentioned, Ixodes scapularis is the vector for Babesia microti, as well as several bacterial pathogens and Powassan virus. Wouldn't it be great if they were all 'headless'?

Monday, November 18, 2019

Case of the Week 569

This week's case was captured by my awesome Parasitology Education Specialist, Felicity Norrie, MLS(ASCP). The following were identified from skin scrapings from a resident of a skilled nursing facility. Identification?


Sunday, November 17, 2019

Answer to Case 569

Answer to Parasite Case of the Week 569: Sarcoptes scabei eggs, larva and adult. Fecal pellets (scybala) are also seen. I love how you can see the larval mite emerging from the egg in this photo:


As several readers mention, scabies is infectious to others, and thus the residents and health care workers in this skilled nursing facility must be evaluated for infection and treated if need be. Anonymous also mentioned that "scabies is not a problem of lack of hygiene but of overcrowding and wherever close person-to person contact is common. Scabies spreads quickly especially in nursing/care homes if no skilled GP or dermatologist is available to diagnose the index Patient, even in highly developed countries." This comments brings up the important point that infection does NOT reflect poor hygiene of the infected individuals. The mite infects all ages, ethnicities and social strata.

Monday, November 11, 2019

Case of the Week 568

This week's case is from Old One - illustrated by him and animated by his son. It features an arthropod that measures a few millimeters in length.
See it in action HERE!
Identification?

Sunday, November 10, 2019

Answer to Case 568

Answer to Parasite Case of the Week 568: Pseudoscorpion or false scorporion, not a human parasite.

This fun little arthropod is occasionally submitted to the clinical laboratory for identification, and may be mistaken as a true scorpion. While both scorpions and pseudoscorpions are arachnids, pseudoscorpions are very small (1 cm or less in length) and lack a tail with a stinger. As sylvie g and Santiago note, pseudoscorpions can occasionally be found in the house, but they don't bite or sting humans, and instead feed on other small arthropods such as booklice.

Thanks again to Old One and his son for the donation of the cool animated illustration.

Tuesday, November 5, 2019

Case of the Week 567

This week's case is from Idzi Potters and the Institute of Tropical Medicine, Antwerp. The following object was seen in a concentrated stool specimen from a 3-year-old toddler with diarrhea (40x objective). It measures 45 micrometers in greatest dimension. Identification?

Monday, November 4, 2019

Answer to Case 567

Answer: Hymenolepis nana egg.
As many of you pointed out, this eggs beautifully demonstrates the filaments arising from the 2 poles of the inner membrane (arrow heads, below image). You can't make it out here, but there are 4-8 of these filaments arising from each pole. You can also nicely see the hooks of the 6-hooked oncosphere:
Some of you may know that humans become infected with this parasite when they ingest infected arthropods. As Sam mentioned, children are a common host - likely due to their tendency to put things in their mouth. Adults can also become infected as Blaine reminds us in his poem:
There once was a chap from Indiana
who with his cereal enjoyed a banana
but with the cereal he did eat
he received an unexpected treat
The cestode known as Hymenolepis nana!

If you do an internet search for "oatmeal" and "bugs," you will find multiple consumer complaints (and some nice YouTube videos) to explain the cereal reference.

Importantly, infection via ingestion of eggs shed in stool (autoinfection or from another person) is also possible, making this a common intestinal cestode infection worldwide.

Sunday, October 27, 2019

Case of the Week 566

Happy Halloween everyone! In honor of this week, I have photos from my annual Halloween party, and a special 'unknown' from Old One. Feel free to guess what my guests' costumes were:

Me and Felicity with (unplanned) matching costumes. Any ideas what we were?
Me and Old One (so great to meet him in person!)
Heather and her 'life cycle' family
Natalia, Zerelda and Pooja representing the exposure and treatment course for this common parasite:
Another take on this fun parasite by Emily and Nick:
Rebecca, Aimee and Emily demonstrating the woes of being a Clinical Microbiology fellow:
Casey and his wife as another classic parasite:
Kyle and his tapeworm family:
There were many more wonderful costumes that I didn't get pictures of (and many that weren't parasite-related that I will post separately on Facebook). 
And last but not least, HERE is Old One's contribution of a hand-drawn case, animated by his son.







Saturday, October 26, 2019

Answer to Case 566

Answer: lots of fun parasite Halloween costumes; here are the 'answers'
   



Monday, October 21, 2019

Case of the Week 565

This week's case was generously donated by Professor Agnes Kurniawan from the University of Indonesia. The following motile structure was reported to emerge from the anus of a man from rural Indonesia. He had no other gastrointestinal symptoms.
You can see its subtle movement here:

This structure was expressed from the submitted object:
Identification?

Sunday, October 20, 2019

Answer to Case 565

Answer to Parasite Case of the Week 565: Bertiella species

This case nicely demonstrates a short chain of proglottids and egg (expressed from the proglottids) of Bertiella - a tapeworm of non-human primates that only rarely infects humans. You can read more about this fascinating parasite at the CDC DPDx website.

The proglottids are very short and wide, thus giving this small segment of proglottids the appearance of 'bow tie' pasta as several of my readers pointed out! (arrows point to some of the individual proglottids)
Bertiella eggs have an internal pyriform apparatus which is difficult to make out in this case. It is better seen in my previous case from 2012: Case of the Week 193.
Thanks again to Professor Agnes Kurniawan from the University of Indonesia who donated this case.



Monday, October 14, 2019

Case of the Week 564

This week's case was donated by Blaine Mathison and Marc Couturier. The following forms were seen on peripheral blood smears. No travel history is available at this time. How would you recommend reporting out this case? Are there any additional studies you would recommend?








Sunday, October 13, 2019

Answer to Case 564

Answer: Mixed Plasmodium ovale and Plasmodium falciparum infection.

This was a very nice clear-cut example of a mixed infection. Often they aren't this clear cut! Thanks to everyone who wrote in with the very nice morphologic descriptions supporting the diagnosis.

Santiago noted that "The first five images show many diagnostic morphologic features: the infected RBCs are enlarged, they have an oval shape with jagged edges (fimbriations), Sch├╝ffner's dots (fine cytoplasmic stippling) are present in their cytoplasm, and infecting trophozoites are compact; these features are consistent with infection by Plasmodium ovale.

The last two images show banana-shaped gametocytes which are diagnostic of Plasmodium falciparum.

My follow-up question was regarding which additional studies, if any, would be recommended. In this case, the morphology is very convincing, and so diagnostic PCR is likely not needed.  However, it was available in this case, and confirmed the diagnosis of P. falciparum and P. ovale mixed infection. Several of you also correctly noted that quantification of parasitemia is also indicated to guide therapy.

Finally, knowing more about the patient would be important to direct patient care. Information to gather would include where the patient had traveled (to determine if there is circulating resistance to commonly-used antimalarials) and if prior antimalarial therapy had been administered. The fact that only P. falciparum gametocytes were present may indicate that the patient had received prior therapy, since the drugs commonly used to treat P. falciparum are not gametocidal. Thus seeing residual P. falciparum gametocytes is not uncommon after successful treatment.  Now that we know that the patient has P. ovale co-infection, primaquine (or tafenoquine) must be administered to eradicate its hypnotzoite stage (dormant stage in the liver).

Thanks again to Marc and Blaine for donating this case.

Monday, October 7, 2019

Case of the Week 563

It's time for our first case of the month by Idzi Potters and the Institute of Tropical Medicine, Antwerp.   The patient is a 50 yo Belgian patient returning from Italy with intestinal complaints coughs up the following worm:

Identification?

Sunday, October 6, 2019

Answer to Case 563

Answer to Parasite Case of the Week 563: Anisakid larva, not Anisakis species.

As noted by Marc Couturier, this case has a "very nice and clearly defined intestinal caecum [or 'cecum' for my United States readers]. Lips are visible on the worm and the general size would point again to an Anisakidae member. Coughing up and the abdominal pain are helpful clinical correlates as well." Blaine also added some helpful information regarding the diagnostic features of anisakids: "Based on the anteriorly-directed cecum, this is either Pseudoterranova or Contracaecum. Unfortunately it is not possible to definitively tell from the image if a posterior ventricular appendix is present (Contracaecum) or absent (Pseudoterranova). Anisakis species lack both." He also noted that all 3 genera may have an anterior boring tooth.

The arrow in the following image points to the anteriorly-facing cecum.

Thanks again to Idzi for donating this beautiful case. I thought that it nicely complimented last week's case, which had a nice clinical (endoscopy) image but lacked a view of the defining morphologic features.


Monday, September 30, 2019

Case of the Week 562

This week's case was generously donated by Dr. David Hernandez Gonzalo. The patient is a middle-aged male who presented with abdominal discomfort and nausea. An endoscopy was performed which revealed the following object in the gastric antrum:
The worm was sent to pathology and was sectioned, revealing the following (H&E):
Identification?

Sunday, September 29, 2019

Answer to Case 562

Answer to Parasite Case of the Week 562: Likely anisakid, given the gross and microscopic appearance and position in the body. This also fits with the clinical history that I held back - this patient was an avid sushi lover!

From the gross image, you can tell that this is a roundworm, and that it appears to be embedded in the gastric mucosa:
You can also see that the caliber of the worm is similar throughout its length. That, as well as the location (stomach), make Trichuris trichiura unlikely. The longer length also allows us to rule out Enterobius vermicularis and the hookworms (which admittedly would also be unlikely in the stomach).

The microscopy is a bit harder to interpret, given that we only have a portion of the worm to examine. What we can make out, however, is the thick eosinophilic cuticle, tall coelomyarian musculature with multiple muscle cells (polymyarian), the intestinal tract that runs the length of the visible portion of the section, and the lack of reproductive structures, which are consistent with an L3 anisakid larva:
I believe that the netting like structure is a section through the muscle cells. We unfortunately can't see the lateral cords (best seen in cross-section) and additional features that would help us identify the anisakid to the genus level (e.g., cecum). This brings us to the conclusion that we always draw from this case, which is to send the worm to the microbiology lab and not the surgical pathology bench!

From Blaine:

Why are pathologists so quick to slice-and-dice
When a diagnosis would be much more precise
If they just left it intact
and the microbiologists have a whack
Alas now a diagnosis is a roll of the dice

Monday, September 23, 2019

Case of the Week 561

This week's case features photos and videos from my fabulous Technical Specialists, Heather Arguello and Emily Fernholz. The following were seen in bronchoalveolar lavage fluid. Identification?


Sunday, September 22, 2019

Answer to Case 561

Answer to Parasite Case of the Week 561: Strongyloides stercoralis L3 (filariform) larvae.

As noted by Florida Fan, the notched tail is clearly shown in this case. Indeed, this is the best example I've ever seen. The notched tail can be used to differentiate the L3 larvae of S. stercoralis with those of hookworm (the latter has a pointed tail).
Old One also pointed out that the filariform esophagus reaches to the midpoint of the S. stercoralis L3 larva. In comparison, the esophagus only reaches to ~1/3 of the hookworm L3 larva. (The CDC has a nice schematic of these differences which you can view HERE.) I can't tell if the background cells in the current case are eosinophils, but peripheral and local eosinophilia are common features of strongyloidiasis.

BW in VT noted that the patient may have acquired infection years ago, and maintained infection via ongoing autoinfection. This is an important component of the S. stercoralis life cycle, as it allows for infection to persist for decades. Should the patient become immunocompromised, the ongoing infection can produce a hyperinfection state, leading to severe morbidity and possible death.

From Blaine: Silly stringy Strongyloides stercoralis stealthily slithers in sputum, spied by sensational Specialists.