Monday, June 26, 2017

Case of the Week 450

This week's case is generously donated by Dr. Kamran Kadkhoda. This little arthropod was discovered in Manitoba, Canada. Identification?

Monday, June 19, 2017

Case of the Week 449

The following object was found in a toilet and submitted to the parasitology lab. Identification? What is the significance of this finding? Images taken by my fabulous education specialist, Emily Fernholz.

Sunday, June 18, 2017

Answer to Case 449

Answer: rat-tailed maggot, family Syrphidae

As nicely described by one of my readers, David Bruce Conn, "This is a rat-tailed maggot, larva of a hover fly belonging to the family Syrphidae. This one may be of the common genus Eristalis. They are not parasitic, but typically live in stagnant water and feed on organic material before pupating. They may incidentally live in toilets and latrines."

The larvae are very recognizable, a long "tail" that contains a breathing tube (respiratory siphon) that connects to the tracheal system and allows the larva to breath oxygen from the water surface. You can also make out antennae and prolegs.

I should note that there have been a few reports of facultative myiasis by this group, but in further investigating these references, I couldn't find any definitive evidence that this occurs (the specimens were all brought in by the patient after being found in the toilet.) Therefore, I think that unless definitely proven, all cases of rat-tailed maggots should be considered incidental findings due to environmental contamination.

Wednesday, June 7, 2017

Case of the Week 448

This week's beautiful case was donated by Florida Fan. These objects were identified during colonoscopy from a middle-aged man. No further history is available. Identification?

Tuesday, June 6, 2017

Answer to Case of the Week 448

Answer: Trichuris trichiura adults

The photos in this case show most of the characteristic identifying features of adult T. trichiura (a.k.a. whipworms) including the classic "whip" shape and eggs with bipolar plugs. The full adult shown is a male as evidenced by his reproductive structures and curled tail. Note that the skinny end is the anterior aspect and not the tail like many students of parasitology would initially assume. The full body of the female is not shown, but you can see characteristic eggs coming out of the uterus.

The stichosome is clearly visible in some of the photos; this prominent glandular organ is seen in trichurids such as Trichuria and Trichinella (as well as some other nematodes) and consists of a row of multiple unicellular cells called stichocytes. The stichosomeruns along the posterior aspect of the esophagus and is a key identifying feature in both intact and sectioned worms. The stichosome opens into the esophageal lumen and has both secretory and absorptive functions.

Monday, May 29, 2017

Case of the Week 447

This week's case is in honor of Memorial Day and was generously donated by Florida Fan. I've actually revived this from a previous case, since the colors (red, white and blue) are so beautiful with Florida Fan's rendition of the modified safranin stain. The red objects seen below were found in stool and measure approximately 10 micrometers in diameter.


Sunday, May 28, 2017

Answer to Case 447

Answer: Cyclospora cayetanensis oocysts

The beautiful red staining of these round oocysts is characteristic, whether using the standard modified acid fast stain or the modified safranin stain.

Monday, May 15, 2017

Case of the Week 446

This week's very timely case was donated by George at Memorial Sloan Kettering Cancer Center. The following objects were seen in a wet mount of a concentrated stool specimen. They measure less than 20 micrometers in dimension and do not have an apparent operculum.

Here is their appearance using iodine:


Sunday, May 14, 2017

Answer to Case 446

Answer: not a parasite; most consistent with mushroom spores.

In this case, the spores were noted in the stool of an individual who had consumed morel mushroom spores, and therefore we can be more specific about the identification.

Mushroom spores are a convincing mimic of parasite eggs. They can be differentiated by a few features, however:
1. Their size is smaller than Enterobius vermicularis eggs - one of their closest mimics.
2. Although in the size range for some of the smaller trematode eggs (e.g. Clonorchis, Metagonimus), they lack an operculum.

Again, special thanks to George who donated these images and reminded me that it is now morel mushroom season!

Monday, May 8, 2017

Case of the Week 445

This week's amazing case was donated by Mr. Boren Huot. This object was seen in a stool specimens from a patient in Cambodia.  Identification? (CLICK ON THE IMAGES TO ENLARGE)

Sunday, May 7, 2017

Answer to Case 445

Answer: Capillaria philippinensis

This case shows an adult worm containing characteristic eggs of C. philippinensis. Note that each egg has a striated wall and bipolar plugs.
Thanks to the CDC DPDx for the photo of the egg shown in the upper right hand corner of the above image.

One reader asked how you could tell C. philippinensis apart from C. hepatica, since both can infect humans. The biggest clue in this case is that the worm was found in stool, whereas the adult worms of C. hepatica are only found in the liver. There are also subtle features of the adult worm and eggs that allow the 2 species to be differentiated.

Thanks again to Mr. Huot for donating a case that we don't get to see very often in the United States.

Friday, April 28, 2017

Case of the Week 444

The week's case was generously donated by Dr. Julie Ribes. The following material was obtained from an ostomy bag.


Thursday, April 27, 2017

Answer to Case 444

Answer: not a parasite; most consistent with banana seeds.

This is something that we commonly see in my lab, and I've previously featured other examples of banana seeds on this blog. Here are the links to 2 previous posts:
Case 139
Case 402

Because I've received some degree of skepticism when I've posted banana seeds in the past, I decided to conduct an experiment to see if I could recreate their appearance through some laboratory digestion techniques. So here was my process:

Step 1. Sacrifice my banana from lunch for the good of science

Note the small immature seeds that are seen in these longitudinal sections. A fun fact - the bananas that we buy in the grocery store have been bred so that the seeds never mature. Wild bananas have large seeds which make the fruit less pleasant to eat.

Step 2. Add bananas to pre-prepared tubes of proteinase K in buffer. (Unfortunately I didn't have any amylase which would have digested the carbohydrates in the banana. However, this was the best I could do to simulate the digestive process). Vortex to mix and then incubate at 56 degrees Celsius while gently shaking (the standard tissue digestion that we use for PCR pre-processing).

Step 3. Check regularly. I first checked every 10 minutes , but very quickly realized that this was going to be a long process. After the first 4 hours, this is how the banana sections looked:

Step 4. Check again, 24 hours later - looking pretty good!
Step 5. Final check - 48 hours. Success! I think that these look nearly identical to our clinical specimen. What do you think?
Close-up view of the seeds (look a lot like the previous cases):

Again, it's not a perfect match since the actual patient specimen was subjected to the entire gastrointestinal digestive process. However, the strings of immature seeds can clearly be seen. Here is how they look microscopically:
You can also appreciate the starch granules of the banana (taken using a 40x and 100x objective):

I hope you all enjoyed this experiment as much as I did!

Sunday, April 23, 2017

Case of the Week 443

This week's case was donated by Dr. Tom Grys. The patient is an immunocompromised man with hemophagocytic lymphohistiocytosis (HLH) and fever. He reports travel throughout the United States and Italy. Bone marrow biopsy revealed the following: