It's the first Monday of the month and time for our case from the Institute of Tropical Medicine in Antwerp! This case is donated by Idzi Potters, as well as Ms. Loranne Lambregts, a new ITM friend and very promising parasitologist!
The following objects were recovered from a patient's scalp. They measure about 2-4 mm and are very motile. What is your identification?
Answer to the Parasite Case of the Week 798: Insect larva; specifically, a flea larva
As noted by Anatoly, this object has the features of a flea larva: "legless, segmented body (13), setae, head capsule, size". The location on the scalp is also supportive of a flea larva - likely from a household pet. Flea larvae are photophobic and are often found deep in animal and pet nests/bedding, carpets, and floor cracks. They are not parasitic on the host, and do not take a blood meal, unlike adult fleas.
Some of you suggested that this could be myiasis, which is caused by dipteran fly larvae. However, fly larvae lack clear body segmentation as seen in this case, as well as a true head capsule and long bristles (setae). Although not shown in this case, flea larvae also lack spiracular plates as seen in dipteran larvae.
In comparison to beetle larvae - another consideration in this case - flea larvae lack legs.
HERE is a nice resource from Animal Patient for additional information (and a rather disturbing video of flea larvae in carpet fibers 😯). The CDC has additional information on fleas, including the diseases that the adult fleas carry and how to get rid of them.
Here is a labelled diagram with some of the key diagnostic features seen in this case:
Thanks again to Loranne Lambregts and Idzi Potters for donating this interesting case!
This week's case was generously donated by Florida Fan and is a fun finding to close the year.
The following objects were found in vaginal secretions (Giemsa stain, 1000x original magnification).
What is your diagnosis? Is there anything special about the image shown here?
Answer to the Parasite Case of the Week 797: Trichomonas vaginalis trophozoites.
Note the diagnostic features, including the small nucleus, 4 anterior flagella, an undulating membrane, and posterior axostyle.
Also, as Idzi noted, we caught one in the process of binary fission! You can see two sets of flagella and two nuclei.
Thanks again to Florida Fan for donating this classic case. Happy 2026 everyone!
Wishing you all a very Happy Holiday Season!
On the 12th day of Christmas my true love gave to me...
Twelve merozoites
Eleven festoons
Ten primary uterine branches
Nine gravid proglottids
Eight eggs-in-packet
Seven coelymyarian muscles
Six raptorial claws
Five antennal segments
Four nuclei
Three intermediate hosts
Two paired alae
And a single species of Ascaris 😎
This week's fascinating (and somewhat gruesome) case is from Dr. Richard Bradbury. The following were seen on a bacterial culture (Chocolate/New York agar) plate after 24 hours of incubation in CO2. The specimen was pus from a perforated eardrum from a child in the Gambia. What are the possible explanations for this finding?
Answer to the Parasite Case of the Week 796: Fly larvae; clinical correlation is recommended.
As many of you noted, there are two main possibilities for this finding:
1. This is a case of aural myiasis, in which a fly laid eggs onto the patient's ear - likely in the setting of a pre-existing skin/soft tissue infection.
2. This represents contamination of the culture plate, in which the fly laid eggs on the specimen after it was collected.
In this case, examination of the patient revealed no evidence of aural myiasis, and therefore #2 is the most likely explanation.
We had a similar case of "agarmyiasis" back in 2018. I encourage you to check out the interesting comments and discussion.
Thanks again to Richard Bradbury for donating this great case!
It's the first Monday of the month and time for our case from Idzi Potters and the Institute of Tropical Medicine, Antwerp. Loranne Lambregts is a new colleague of Idzi's and contributed to this case, identifying the object of interest below that was submitted for parasite identification in their lab. It measured approximately 1.5 cm in greatest dimension and was still moving when received! Here it is pressed between two glass slides:
Answer to the Parasite Case of the Week 795: Taenia saginata/suihominis gravid proglottid.
As noted by Anonymous, Patrik, Antoine A, Florida Fan, Menzler, and others, we have a proglottid of Taenia saginata/Taenia suihominis (formerly known as T. asiatica) characterized by >12-13 primary uterine branches on each side of the central uterine stem and a Taenia spp. egg characterized by an internal hooked oncoschere and a thick radially striated outer shell. Assuming the image of the egg was acquired using a 40x objective, we can estimate a size of 35 micrometers in greatest dimension which is consistent with Taenia species. We don't have a patient travel history, so I would sign this case out as "Taenia saginata/Taenia suihominis".
This beautiful preparation shows a fresh proglottid pressed between glass and backlit to show the characteristic branching pattern. I particularly like this technique since it requires only minimal manipulation of the proglottid. It can easily be done with a fresh proglottid, but preserved proglottids need to be cleared and softened through exposure to lactophenol or other preparation.
Injecting India ink into the lateral genital pore of Taenia proglottids can also be used to highlight the uterine branches, but we don't perform this in my lab given the potential infectious risk associated with T. solium.
Regarding motility as a diagnostic feature - I dug into this in Case of the Week 789 by scouring the old literature and found only anecdotal evidence. However, it does seem that Taenia saginata proglottids are more likely to be motile than T. solium. I can't speak to T. suihominis, so if anyone has information to share on this species, I would love to hear it.
Thanks again to Idzi and Loranne for donating this great case!
This week's case is from Dr. Steven Ruhoy and Tracie Rose. The patient is an elderly woman with a very itchy rash which is worse at night. The family practitioner noted excoriations on the plantar aspect, but did not see any definitive burrows. She performed a skin scraping which revealed the following on H&E-stained histologic section. What is your identification?
