Case of the Week 576

Happy New Year! Our first case of 2020 was provided by Heather Arguello, my awesome Parasitology Technical Specialist. The following worm was found in a specimen obtained during colonoscopy. It measured approximately 2 mm long. Identification?

Answer to Case 576

Answer to Parasite Case of the Week 576: Enterobius vermicularis (a.k.a., pinworm), adult male

Thanks to all who wrote in with the correct answer. Florida Fan noted the presence of several identifying features: cephalic alae confirming the identity of pinworm in this adult nematode, and the curved tail with visible copulatory spicule defining the gender as male.

Meanwhile, Idzi reminded us that Enterobius vermicularis was formerly known as Oxyuris vermicularis. This is why you will sometimes see the infection referred to as oxyuriasis. Finally, Marc shared that he knew the answer but couldn't seem to "pin" it down 😉.

Case of the Week 575

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

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)

Case of the Week 574

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

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!

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?

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.

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?

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!