Sunday, August 18, 2019

Case of the Week 557

This week's case was donated by Florida Fan and one of his coworkers who found this beauty in some fresh salmon:
Posterior end:
 Anterior end:

Monday, August 12, 2019

Case of the Week 556

This week's case was donated by Dr. Neil Harris and Dr. Stacy Beal. The patient is an infant with a history of tracheobronchomalacia and "eosinophilia" on prior bronchoscopy. A routine complete blood count was negative without evidence of peripheral eosinophilia. The following structures were seen on a Giemsa-stained bronchoalveolar lavage specimen using the 100x objective. They have a diameter of 1-3 micrometers. Identification?

Sunday, August 11, 2019

Answer to Case 556

Answer to the Parasite Case of the Week 556: Curschmann spirals

Curshmann spirals can be a very pretty, but sometimes confounding parasite mimic in sputum, BAL and bronchial lavage specimens. They are spiral-shaped plugs of mucus from obstructed bronchioles, and are seen in patients with asthma and other conditions affecting the airways (e.g. tracheobronchomalacia as seen in this case). Although they can take on a roundworm-like appearance, they can be differentiated by their lack of defined morphologic features such as a cuticle and internal structures. Here is a striking photo from a different case (Papanicolaou stain):

Friday, August 2, 2019

Case of the Week 555 - a Special Challenge!

Dear readers,
I am excited and humbled to be posting my 555th Parasite Case of the Week. I am continuously inspired by your comments, questions, and the rich discussion that occurs with each post. To mark this occasion, I'm asking you all to comment on ways that parasites relate to the number 5. I'll start you off with two that were previously suggested to me when I thought up this challenge:
  1. Pentatrichomonas hominis is a nonpathogenic intestinal flagellate named for its 5 flagella (penta from the Greek pente, meaning five + trich, pertaining to hair [flagella]). By Dr. Neil Anderson
  2. There are 5 lobes of the human lung, and all can be infected by Paragonimus species. By Brian Duresko
Feel free to be as creative as you'd like. 5-lined poems (e.g. limericks) are also accepted! I will post all of the responses next Friday, so you have all weekend and next week to think of ideas. Enjoy!

Thursday, August 1, 2019

Answer to Case 555 - Parasites and the Number Five

Wow - we received so many excellent comments on how parasites and the number 5 go together! Here are many of them - in no particular order - for your viewing pleasure:
  1. Pentatrichomonas hominis is a nonpathogenic intestinal flagellate named for its 5 flagella (penta from the Greek pente, meaning five + trich, pertaining to hair [flagella]). By Neil Anderson and Bernardino Rocha.
  2. There are 5 lobes of the lung, and all can be infected by Paragonimus species. By Brian Duresko.
  3. The are 5 Plasmodium species that are responsible for the bulk of malaria in humans: P. falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi (the latter is a zoonotic parasite and important cause of malaria in regions of SE Asia). By Aimee Boerger, Nipunie Rajapakse, and LS.
  4. Pentastomes have a name meaning "five openings". Although having a single mouth, there are 2 pairs of hollow fang-like hooks beside the mouth. These fangs can be retracted into slits giving the appearance of 5 mouths. By Old One.
  5. Quintan fever, also known as trench fever, is due to infection with the bacterium Bartonella quintana, and is transmitted by the body louse, Pediculus humanus humanus. The infection is characterized by fevers that recur every five days; hence the name of the bacterium and the resultant disease. By Kristin Nagaro.
  6. The gametocytes of Plasmodium vivax appear in the blood ~5 days after the liver stage, whereas it takes 10-12 days for P. falciparum to appear. Thus, P. vivax infection can be acquired by mosquitoes at the very first blood stage cycle, and this may confer a transmission advantage for P. vivax over P. falciparum. Plasmodium vivax has the most widespread distribution of the human malaria-causing Plasmodium spp., and the early gametocytemia will have important implications for malaria eradication. By BW in Vt.
  7. Pentamidine is a drug used to treat some protozoal infections such as leishmaniasis and African trypanosomiasis. The first part of the drug's name comes from the pentane component which has 5 carbon atoms (C5H12). By Andy Norgan.
  8. Human parasites can be divided into 5 major groups: protozoa, platyhelminthes, acanthocephala, nematoda, and arthropoda. By Bernardino Rocha.
  9. The 5 main symptoms of giardiasis are diarrhea, abdominal pain, fatigue, weakness, weight loss. By bks. I use a similar one - the 5 "F's" of giardiasis: Foul-smelling Fatty Feces that Floats and Flatulence.
  10. The US Centers for Disease Control and Prevention has targeted 5 neglected parasitic infections (Chagas disease, neurocysticercosis, toxocariasis, toxoplasmosis, and trichomoniasis) as priorities for public health action, based on the numbers of people infected, the severity of illnesses, or our ability to prevent and treat them. Anonymous.
  11. Toxoplasmosis, a protozoal infection, in one of the ‘infamous 5’ TORCH infections that cause congenital abnormalities; the acronym stands for Toxoplasmosis, Other (syphilis, VZV, parvovirus b-19), Rubella, CMV, and Herpes simplex virus infections. By Vik Holenarasipur and Anonymous.
  12. Human bot flies (and other insects) have 5 eyes - 2 are compound and 3 are simple. This paper wasp (below) is not a parasite, but was willing to pose for a photograph of its five eyes. By John Carlson (@JohnCarlsonMD).
There were also some wonderful stories and poems with 5 lines or words/line:
From Blaine Mathison:

Many of the earth-based religions use the pentagram to represent the Five Elements: Spirit, Air, Water, Earth, and Fire. Many religious beliefs are grounded in scientific phenomena that were unknown at the time. What many people do not know, is the earth religions are rooted in Parasitology!

Spirit represents Loa loa and its microfilariae that circulate in the body. This belief is shared with Voodoo as the term 'loa' is a spirit in Voodoo religion.

Water represents Schistosoma, as water is natural reservoir for which the spirit enters the body.

Fire represents Trichomonas vaginalis, as people occupied by this spirit often have a burning sensation.

Earth represents Strongyloides stercoralis as they enter the body from the soil. Some liken Strongyloides to Mother Earth as she can create life in a host without a male counterpart.

Air represents Plasmodium, as it is carried by flying arthropods! And its erythrocytic cycle created periods of suffering and relief, as a reminder Life is a balance of Good and Evil.

If you have read this far, yes I am being silly and having fun, letting the creative juices overflow a bit :-D
From Old One:

Now in Rochester’s sunny clime
Where I used to spend me time
A-servin’ the majestic Clinic Mayo
Of all that brilliant crew
The finest Doc I knew
Was Dr. Pritt, Diagnostic Mistro

It was Dr. Pritt, Pritt, Pritt
Most skillfull Parasite Gal, Dr.Pritt
Hi! Slippy Hitherao
Diagnosis please, Panee Lao
And be quick, about it. “Lickety split” Dr. Pritt

This noble Parasite Gal
Has a blog that’s really swell
Which has been followed round the globe for many years
She’s now at 555
And if I stay alive
I expect to see 666. Note to Satan, please stand clear

If I’m ever on campaign
Licking boots and water green
I will make tracts to Dr. Pritt at Mayo Clinic
She’s the one to check my blood and stool
Mama didn’t raise a fool
For I’ll surely have a case most parasitic
Also from Old One:

Zen queries to Madam Ascaris
What is the sound of one hand clapping?
What does a three lip smile look like?

A happy worm is the ascarid
Swims in chyme and squirms like a squid
As happy as she is
She has but one regret
“How do you smile with three lips on the tip of ones head?”
From Sir Galahad,
5 verses of J.Swift:

Big fleas...
Big fleas have little fleas
Upon their backs to bite' em
And little fleas have lesser fleas
And so, ad infinitum

(Filastrocca di Jonathan Swift
Disegno di Robert Hegner, 1938)

Monday, July 29, 2019

Case of the Week 554

This week's case was generously donated by Florida Fan. The following are seen on Giemsa-stained thick and thin blood films. No history is immediately available. Diagnosis? Any additional information you would like?

Sunday, July 28, 2019

Answer to Case 554

Answer to Parasite Case of the Week 554: Babesia species. Without a travel history, the differential diagnosis includes Plasmodium falciparum malaria given that only ring forms are seen and there is a high parasitemia; however, the following features are supportive of babesiosis:
1. Multiple (4) small forms within a single cell that are not a clear schizont form of Plasmodium.
2. Easily-identified extracellular forms.
3. Lack of malaria pigment

As Blaine mentioned, the rings are not thin and delicate as would normally be seen with P. falciparum infection. While thicker rings are commonly seen in 'older' blood (i.e., blood that was >24 hours old), we would expect to see malaria pigment in these cases, and none is seen in this case.

One reader was favoring babesiosis, but was swayed from this diagnosis by the lack of maltese cross (tetrad) forms. However, it's important to note that most cases of babesiosis will NOT have maltese cross forms. Instead, the diagnosis must be made on the other features listed above, in addition to the commonly-seen pleomorphism of the parasite forms in babesiosis. Interestingly there wasn't a lot of pleomorphism in this case.

Thanks again to Florida Fan for donating this informative case. It reinforces the need to get a travel history whenever possible (he later learned that the patient had not traveled outside of the United States), and to consider both babesiosis and malaria in the differential when seeing intraerythrocytic parasites.

Monday, July 22, 2019

Case of the Week 553

This week's (interesting but somewhat disturbing) case was generously donated by Dr. José A. T. Poloni. The following was submitted from a fresh (unfixed) stool specimen. Most likely identification?

Sunday, July 21, 2019

Answer to Case 553

Answer to Parasite Case of the Week 553: Ascaris lumbricoides

The overall appearance and large size of this nematode are strongly suggestive of A. lumbricoides, given that this is a human stool specimen. As Sam mentioned, examining the anterior end for the characteristic 3 fleshy lips common to all ascarids, and examination of the stool for eggs would allow for confirmation of the identification.

Here are some images from other cases to show these characteristic features:
Adult with 3 fleshy lips from Case of the Week 479:
Mammillated and decorticated eggs from Case of the Week 550

Thanks to all that wrote in with the answer, and to Dr. Poloni for donating this case!

Monday, July 15, 2019

Case of the Week 552

This week's case is from Blaine Mathison. The following were seen on a trichrome-stained stool specimen. They averaged 5 to 7 micrometers in greatest dimension. A Giardia antigen test was positive.


Sunday, July 14, 2019

Answer to Case 552

Answer to Parasite Case of the Week 552: Enteromonas hominis

This was a tough one! Not a surprise since it came from Blaine 😊
The organisms shown are small trophozoites, measuring only 5 to 7 micrometers in greatest dimension, and no cysts were seen, thus making identification a bit challenging. While I think that some of these trophozoites look a bit like Chilomastix mesnili (for example, some of the larger forms in the first image), I think that the smaller size, less elongated shape without a well-defined terminal point, and larger karyosome is more consistent with E. hominis. 

The CDC doesn't have any good trophozoite photos on the DPDx webpage, but Henry Bishop kindly shared these following beautiful photos with me awhile back. They are a bit clearer than in the current case and nicely demonstrate the diagnostic features.

So what about that positive Giardia antigen? A bit of a red herring in this case. Giardia was actually present in this case, but not included in the images I presented.

Tuesday, July 9, 2019

Case of the Week 551

This week's case was generously donated by Florida Fan and is very appropriate for this time of the year!

The following objects were seen on a stool specimen that had been stained by Wright-Giemsa to look for fecal leukocytes (total magnification 1000x). Preliminary identification? What additional stain would you like to perform to confirm your diagnosis?

Sunday, July 7, 2019

Answer to Case 551

Answer to Parasite Case of the Week 551: Cyclospora cayetanensis oocysts.

This is an unusual preparation in that we don't usually see C. cayetanensis oocysts in Giemsa-stained preparations. Therefore, confirmation using a conventional stain such as modified acid fast or modified safranin would be indicated. The diagnosis can be made by the shape and size (~8 micrometers) in diameter.

Thanks again to Florida Fan for sharing this interesting case!

Monday, July 1, 2019

Case of the Week 550

Happy July everyone! Here is our first case of the month by Idzi Potters and the Institute of Tropical Medicine, Antwerp. The following objects were seen in a concentrated wet prep of a stool specimen from an international adoptee from Ethiopia. They measure approximately 60 micrometers in greatest dimension. Identification?

Sunday, June 30, 2019

Answer to Case 550

Answer to Parasite Case of the Week 550: Ascaris lumbricoides eggs, decorticated

Kudos to everyone who took the time to write in with their answer. All responses were correct! And I really enjoyed hearing about the different layers of of nematode eggs from Old One and Blaine. Here is some of the information they shared in their comments, along with some definitions:

Decorticated - To remove the bark, rind, or husk from; i.e., to remove the outer mammillated layer
Mammillated - Having relatively small protrusions from the exterior, most commonly the surface

This case happened to have both mammillated and decorticated eggs, with a large number of the latter:
When only decorticated eggs are seen, they can be confused for other helminth eggs such as hookworm and Schistosoma japonicum. Fortunately the size and thick shell can be used to reliably differentiate them.

So what are the layers of a nematode egg?  There are several (from outer to inner), as described by Old One and Blaine, with a few comments from my own research:

  1. Mucopolysaccharide/protein coat - not present in all nematode eggs; this is an exogenous product of the nematode uterus and what is referred to as the 'mammillated' albuminous layer. It is unique to each species and often stained by the bile salts of its host (yellow, orange, to brown). It is often uniquely textured during its creation. This layer may be friable, hence the decortication seen in this week's specimen. 
  2. Vitelline layer - derived from the vitelline membrane of the fertilized oocyte. It envelops the entire egg (including the bipolar plugs of Trichuris eggs). Of note, it can be selectively removed with chemical treatment, with the eggshell remaining intact (and contents remaining viable)
  3. Chitinous layer - this is the rigid layer that gives the eggs its shape. 
  4. Chondroitin proteoglycan layer - originally thought to be a lipid-rich layer
Layers 2, 3 and 4 are now commonly referred to as the trilaminar outer eggshell that we are well familiar with. Additional inner layers have since been identified, including a lipid-rich layer which serves as a permeability barrier for the developing embryo, and an innermost peri-embryonic layer. 

I had a lot of fun digging through the old and new literature to find all of this information, so thank you Old One and Blaine for the impetus to do so! NIH investigators have published a nice chapter of the structure of the C. elegans shell that is freely available HERE.

Monday, June 17, 2019

Case of the Week 549

This week's rather creepy and very cool case was donated by Dr. Matt Bolek and Christina Anaya. While the host shown here is not a human, this parasite emerging from the cricket is occasionally submitted to human clinical parasitology laboratories. What is its significance for human health?

Sunday, June 16, 2019

Answer to Case 549

Answer to Parasite Case of the Week 549: "Gordian" or "horsehair" worms, belonging to the group Nematomorpha. I had asked what its significance is for human health; this was a trick question, since gordian worms have no direct clinical significance, other than scaring people when they are found in toilet water! When submitted to the clinical parasitology laboratory, they can easily be differentiated from other large worms such as Ascaris lumbricoides by their long slender bodies:
I have to admit that I was amazed by how many worms emerged from the poor cricket in this fascinating video donated by Matt and Christina. The good news is that the cricket survived the ordeal and went on to chirp another day!

There is an excellent description of this group of worms on the University of Kentucky entomology website.

Monday, June 10, 2019

Case of the Week 548

This week's case was generously donated by Dr. Tara Ness, with filming credit to the Lab Hlathi Team in eSwatini. The following arthropod was found in the urine specimen of a man with HIV and a history of dysuria. Identification?

Sunday, June 9, 2019

Answer to Case 548

Answer: Mite, most likely Dermatophagoides species (dust mite).

As mentioned by several readers, we are lacking sufficient details to make a definitive identification. However, we can conclude that this is a contaminant in this specimen and not a cause of the patient's symptoms. As Blaine mentioned, this is a "Conta-mite-nt"!

Some readers mentioned that Sarcoptes scabei should be considered. While this is also a mite, its distinctive features, including its short legs and overall body shape, allow for differentiation from Dermatophagoides:

Thanks again to Dr. Ness and her lab for donating this case.

Monday, June 3, 2019

Case of the Week 547

Here is our monthly case by Idzi Potters and the Institute of Tropical Medicine, Antwerp.

The following 1-cm long structure was extracted from a Belgian patient returning from Ghana. Identification?

Sunday, June 2, 2019

Answer to Case 547

Answer to Parasite Case of the Week 547: Cordylobia rodhaini, also known as Lund's fly.

As noted by Bernardino, this is a 3rd instar larva, with a characteristic shape, size, irregularly-placed, weakly-pigmented cuticular spines and spiracles for this species. The more sinuous spiracles allows us to differentiate this from Cordylobia anthropophaga, the "tumbu fly" which is more commonly seen on humans. Both are found in the African subtropics.

From Old One:
Hooray for Bernardino a wiz at diagnostics
Lund’s fly no match for his skillful forensics
The folks on the blog all think he is swell
Never missing his mark, the new William Tell

You can read all about this fascinating parasite in Idzi's latest publication which is freely available HERE. An important point to note is that the adult flies of C. rodhaini and C. anthropophaga deposit their eggs on soil or clothing. Contact with the warm-blooded host then causes the larvae to hatch and penetrate the skin. This is why it is common practice in endemic areas to iron your clothes - including undergarments - after taking them off the line! This important point can be remembered from Blaine's fun poem:

In Africa, if you allow your laundry to air dry
Make sure you iron it! Wanna know why?
'cuz this diabolical dipteran lays its eggs on fomites
especially on clothes and sheets dried by sunlight
and that's how you get exposed to the tumbu fly!

Thanks again to Idzi for sharing this case with us!

Tuesday, May 28, 2019

Case of the Week 546

This week's case has been generously donated by Blaine Mathison at ARUP. Two different types of objects were seen in a trichrome-stained stool specimen that was screened by a digital slide image and machine learning platform. How did it do? Did it find real parasites?

The following objects are approximately 8 to 13 micrometers in diameter:

These objects are 10 to 15 micrometers in greatest dimension.

Sunday, May 26, 2019

Answer to Case 546

Answer: Blastocystis sp. and Entamoeba sp.

From Blaine: These images were captured by software trained to detect intestinal protozoa in trichrome-stained stool specimens. The final report was Entamoeba histolytica/E. dispar and Blastocystis sp. It is difficult to determine the species of Entamoeba from only four examplars, but the even peripheral chromatin and discrete karyosome are supportive of E. histolytica/E. dispar which is how this case was signed out from both the slides and the whole-slide scanned image. I see a lot of respondents placing weight on the cytoplasm, which I always take as a ‘soft’ feature – I prefer peripheral chromatin.

The software we are training (still in validation stage) is designed to detect Entamoeba based on the nucleus (the amorphic forms of trophozoites created too many false positives when we tried to detect the entire organism). The software is not designed (at least at the moment) to identify the Entamoeba to the species level. All slides flagged as positive with a high score of being positive are to be manually backread for confirmation and species-level ID. The software is more of a screening tool, in hopes of cutting down manual read of 70% of our negative trichromes.

So to those who questions if artificial intelligence is going to make parasitologists obsolete - the answer is "no"! Dr. Marc Courturier assures us in his comment: "Have no fear. We will all have jobs as expert parasitologists. This technology that Blaine and I have been working on will make our work MUCH easier, faster, and more accurate. And fun...because lets face one likes sitting for 8 hours at a scope.The future is bright for parasitology."

Thanks again to Blaine (and Marc) for donating this case!

Sunday, May 19, 2019

Case of the Week 545

This week's case was donated by Dr. David Pritchard. The following worm was noted in the toilet of a patient with an extensive international travel history. Likely identification?

Saturday, May 18, 2019

Answer to Case 545

Answer: Not a human parasite: earthworm (Phylum Annelida, subclass Oligochaeta, Family Lumbricidae). It could very well be a Lumbricus species as some readers suggested, but I don't know enough about the different genera of earthworms to tell you for sure. Perhaps a knowledgeable reader can educate us on this topic?

So, wow, I've been on a roll with these parasite mimics! I'll try my best to include some true parasites in upcoming posts. Those of you who have followed this blog for a while probably know that I am fond of mimics - probably because they are so commonly seen in the clinical microbiology lab and provide an interesting challenge to clinicians, patients and laboratorians alike. In this case, I'm sure the patient wouldn't have hesitated to identify this object as an earthworm if it had been in a bait and tackle shop. It's when mimics end up in unfamilar settings (i.e., the toilet bowel) that they become a cause for alarm.

So how did this earthworm end up in the toilet? My plumber friend tells me that this is not an uncommon occurrence since pipes break due to the wear and tear of being in the ground. Tree roots, it would seem, are the enemy of sewage pipes.

For those of you wondering how to tell an earthworm apart from other large worms (e.g., Ascaris lumbricoides), here are some of the defining features that are not seen in human parasites:
1. Clitellum - the thickened glandular non-segmented portion of the earthworm's body found in sexually-mature adults.
2. Segmented body with setae. Setae are the small bristles found on each segment that help the worm move through soil.
3. A mucin-secreting epithelial layer beneath a thin cuticle. This is best appreciated on histopathologic exam; you can see a nice example in my previous CASE 234.

With that, I'll leave you with an interesting 'conversation' between two of our faithful readers, Old One and Florida Fan:

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 here is 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. Enjoy!

Monday, May 13, 2019

Case of the Week 544

This week's case features an interesting finding in a concentrated stool specimen. The photos are from my awesome technical specialist, Heather Arguello. The individual structures are approximately 25  micrometers in length, while the longer tubular structure is 330 micrometers long.


Sunday, May 12, 2019

Answer to Case 544

Answer to Parasite Case of the Week 544: Ascus with ascospores (presumed mushroom) spores. Interestingly, it is morel season in many parts of the United States, and these appear to be a perfect match to morel ascospores!
While we commonly see mushroom spores in stool specimens (and have to differentiate them from  helminth eggs), and intact ascus (a sac in which the spores of ascomycete fungi develop) is rarely seen. Thanks again to my lead tech Heather who took the time to snap a photo of this cool finding!

Monday, May 6, 2019

Case of the Week 543

This week we are featuring our monthly case from Idzi Potters and the Institute of Tropical Medicine, Antwerp.

The patient is a 15 year old boy returning from swimming camp, who presents with several-day history of profuse watery diarrhea. A stool specimen was submitted for parasite examination, and multiple small (3-6 µm), round structures were identified. The following photos are taken after:

1. Negative fuchsine staining according to Heine (brightfield microscopy)
2. Negative fuchsine staining according to Heine (phase-contrast microscopy)

3. Ziehl-Neelsen staining (“cold” modified technique)