Monday, December 30, 2019

Case of the Week 575

Happy New Years everyone! Can anyone tell me who this little arthropod is?

Sunday, December 29, 2019

Answer to Case 575

Answer: Ctenocephalides canis. This nice little male flea has characteristic pronotal and genal combs, and a more rounded head than C. felis. There are other important differentiating characteristics as well (you can read about them HERE) and so identification to the species level is best performed by experts.

Thanks to Anon for the lovely poem. I should have thought of this for Christmas!
Anonymous said...
a little late, I would have preferred a fleas navidad..
fleas navidad, fleas navidad
oy contraro fleas are so bad.
I want to wish you a itchy Christmas
I want to wish you a itchy Christmas
from the bottom of my scratch...
Happy New year, all....

Wishing you all a very happy, healthy and productive New Year, full of fascinating parasite cases!
Bobbi (a.k.a. ParasiteGal)

Monday, December 23, 2019

Case of the Week 574

Happy Holidays to all of my readers! Can anyone tell me who this little arthropod is?

Sunday, December 22, 2019

Answer to Case 574

Answer to Parasite Case of the Week 574: Holiday bedbug, most likely Cimex lecturlaris. We seem to have some 'controversy' about the nomenclature here; Eagleville identified this as Cimex lectularius (subspecies Santaclausus), whereas Idzi identified it as Cimex santaclarius. I will rely on my taxonomy experts to tell us which is correct 😉.

For now, I'll leave you with this festive poem from Blaine:
 Dashing through the sheets
on six segmented feet
O'er the pillows they go
sucking blood all the way
lap lap lap

Pointed beak goes down
after you turn off the lights
oh what fun it is to suck
blood from a host tonight

Oh, bed bugs suck
bed bugs suck
bed bugs suck your blood
Just be glad
they don't spread disease
or any nasty crud!

Monday, December 16, 2019

Case of the Week 573

This week's case is Dr. Charles (Chuck) Sturgis. He noted the following structures on a Papanicolaou-stained anal Pap smear (performed for cancer screening). They measure approximately 14 micrometers in length. Identification?

Sunday, December 15, 2019

Answer to Case 573

Answer to the Parasite Case of the Week 573: Giardia duodenalis (a.k.a. G. lamblia, G. intestinalis) cysts

This is the third time I've seen this finding in an anal pap smear - each time it was an unexpected, incidental finding. Despite this being a stain not commonly used in the parasitology laboratory, all of the key morphologic features including the nuclei, central axonemes, and curved median bodies, can be seen.

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?

Sunday, December 8, 2019

Answer to Case 572

Answer to Parasite Case of the Week 572: Tungiasis, due to the parasitic female sand flea. As Blaine mentioned, it is most likely Tunga penetrans, but in Brazil, Ecuador and Peru, there is a second species infesting humans: T. trimamillata. It's not possible to tell the two species apart from this image alone.

What we can see from this beautiful image by Dr. Maia is an anterior portion of the female Tunga flea that had been curretted from the patient's foot lesion.

Infestation with the Tunga flea is called tungiasis. From anonymous: Tungiasis "is one of our favorite words as sounds very nasty and rolls off the tongue very nicely." Indeed, tungiasis is a particularly nasty, painful, and potentially debilitating condition where the female flea burrows head first into exposed skin - often between the toes and under nail beds. Santiago reminds us that medical treatment is ineffective, and "prevention is thus the best way of controlling the disease, preventing the parasite from penetrating the intact skin. But who wants to wear shoes at the beach?"

Thanks again to Dr. Maia for sharing this case!

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

“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!