Case of the Week 800

Welcome to our 800th case! Given the occasion, I thought we deserved something spectacular, and these images from Heather Morris definitely fit the bill. These worms measure ~1 cm long. What is your diagnosis?

Case of the Week 799

This week's case was donated by Drs. Jacob Rattin and Akeesha Shah. The patient is an elderly male with a history of bladder cancer, status post cystectomy, who was undergoing screening urine cytology. The specimen was collected from a urostomy bag from an ileal conduit. The following forms were seen on the Thin Prep specimen. They measure 50 to >120 micrometers long. What is your diagnosis? 

Answer to Case 799

 Answer to Parasite Case of the Week 799: Not a parasite; plant material consistent with guar gum.

Guar gum (a.k.a. guaran) is a galactomannan polysaccharide extracted from guar beans. It has thickening and stabilizing properties that are useful for food, feed, and industrial applications. In medicine, it is often used as an adhesive to keep ostomy bags attached to the skin. This is how it likely got into the specimen from this patient. 

Some readers queried if this plant material could have originated from the intestinal tract, given that the patient has an ileal conduit. However, in looking into the way an ileal conduit is created, we can see that it is disconnected from the GI tract and therefore would not contain food material.

For fun, I decided to investigate the microscopic appearance of guar gum using common parasitology stains. Below are my results using a simple wet prep, modified trichrome (Ecostain) stain, and Giemsa stain. Note that it is birefringent with polarized light, as is most plant material. 

This interesting finding has been reported before by Nomani et al. Thanks again to Drs. Rattin and Shah for donating this interesting case!

Case of the Week 798

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 Case 798

 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: 

Flea larvae range from 1 to 5 mm based on their instar stage.

Thanks again to Loranne Lambregts and Idzi Potters for donating this interesting case!

Case of the Week 797

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 Case 797

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!

Happy Holidays!

 Wishing you all a very Happy Holiday Season!

From Blaine Mathison: 

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 😎

Case of the Week 796

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 Case 796

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!