Tuesday, June 21, 2016

Case of the Week 401

This week's case is in honor of Father's Day, which was just 2 days ago, as well as Mother's Day, which was in May.

The following were submitted to my laboratory for identification. The larger of the 2 arthropods was still alive. Identification?
Here are some close-up shots:

 Thanks to Emily Fernholz for taking these gorgeous photos!

Monday, June 13, 2016

Case of the Week 400

Welcome to our 400th Parasite Case of the Week! To celebrate the 400th case, I thought I would dedicate this post to education in parasitology and share with you 5 of my favorite parasite teaching tools.

1. Embed arthropods and worms in casting resin, using products purchased at your local arts and crafts store. I've used Castin' Craft in the past, but there are other options out there as well. Here is one of my creations - adult Ixodes scapularis ticks (in different stages of engorgement) in a small petri dish:

Embedded arthropods are great for teaching because they are durable (e.g. their legs don't fall off from being manipulated over and over again), and you can easily examine both their dorsal and ventral aspects. If you're feeling really creative, then you can also make them into little works of art - or even jewelry (start a fun new trend). You can buy molds in every shape and size under the sun.

2. Find some anisakids in frozen (or fresh) cod. I have the best luck with Atlantic cod; in every bag of 10 fillets, I usually find at least 1 worm. I let the fillets thaw in the refrigerator and then use blunt dissection to find the coiled larvae. I put the fish (with anisakid) on a plate for display in my teaching lab. It's a great way to get medical students, residents, techs, and clinicians interested in parasitology.

For added fun, have a fish dissecting party! Here are some of my awesome pathology residents, who came up with this idea all on their own.

3. Buy some medicinal leeches (Hirudo medicinalis) at your hospital pharmacy. Like the cod, these also make a great display for a parasite teaching laboratory. You can use them as an example of an ectoparasite, talk about the anticoagulant they produce (hirudin - used medicinally), discuss their fascinating history (past and present) in medicine, and also discuss why it is necessary to give prophylactic antibiotics to recipients of leech therapy (to prevent sepsis with Aeromonas - a commensal bacterium in the gut of medicinal leeches).

Yes, it's a display with shameless 'ick' factor, but it's great for capturing the attention of medical students and clinicians alike.

4. Learn some basic entomology skills. Try dragging for ticks, collecting black fly (Simulium sp.) larvae from a fast-flowing stream (below), or learn how to mount insects professionally for teaching purposes (compliments of Blaine Mathison).

5. Last, but not least, have a parasite potluck, with treats decorated with your favorite (candy) parasites.

Cupcakes by Dr. Rachael Liesman, my Clinical Microbiology fellow:

Malaria cookies by my Education Specialist, Emily Fernholz

Cakes from the Mayo Medical Students! Coconut rectum, Giardia duodenalis, Reduviid bug transmitting Trypanosoma cruzi through its feces, Strongyloides stercoralis on a stool agar culture, and a strawberry cervix.

So for my questions this week: What parasites are associated with a 'coconut rectum' and 'strawberry cervix'?

Sunday, June 12, 2016

Answer to Case 400


1. Parasite associated with 'coconut rectum' - Trichuris trichiura. This description refers to a prolapsed rectum on which numerous adult worms attached to the rectal mucosa can be seen.
(Image courtesy of the CDC Public Health Image Library)

2. Parasite associated with 'strawberry cervix' - Trichomonas vaginalis. This description refers to the punctate hemorrhages seen on the infected cervix which purportedly look like a strawberry.

(Image courtesy of the CDC Public Health Image Library)

Sunday, June 5, 2016

Case of the Week 399

Wow, we're almost at 400 cases! I will have to think of something extra special for next week. Meanwhile, here is classic finding in a trichrome-stained stool specimen (1000x).


Saturday, June 4, 2016

Answer to Case 399

Answer:  Dientamoeba fragilis

This organism has an overall structure like an amoeba, but has an internalized flagellum, and is therefore most accurately characterized as a flagellate. It is sometimes referred to as an amoeboflagellate. As nicely described by Florida Fan, D. fragilis has a characteristic nucleus with 'fragmented' appearing chromatin. It commonly has 2 nuclei, but may also have 1, as seen in some of the organisms in this case.

Sunday, May 29, 2016

Case of the Week 398

We had a number of great arthropod cases in the past few weeks! Here's one that had us stumped for a little while:

The following live objects were noted on a tampon brought in by a female patient to her  gynecologist. The patient also reports that these objects are being shed in her stool and urine.

Examination of the specimen revealed a clearly-used tampon containing the following objects - many that appeared to be superficially embedded in the cotton fibers:

Identification? What additional information would you like?

Saturday, May 28, 2016

Answer to Case 389

Answer:  Fly larvae; most likely representing involvement of the tampon in the environment rather than in the patient.

As described by Florida Fan and Anon, this is supported by the presence of different larval stages and a possible pupa with respiratory structures. Pupal casings were also seen, indicating that at least 1 adult fly had hatched. There also appears to be more than 1 genera of fly present.


If this had all been in the patient (e.g. facultative or obligatory myiasis), then we would have expected the larvae to be in the same stage and of the same genus, unless there was a wound exposed to the environment which different flies were continuing to lay eggs in.

Discussion with the physician revealed that the patient did not have a wound, and that the tampon had been brought in by the patient, rather than being removed by the physician. Therefore, the most likely explanation for this case is that the tampon had been discarded in an open trash can that was exposed to flies. The patient is now likely traumatized by finding the tampon covered in fly larvae, and is understandably concerned that she is also passing larvae in her urine and vaginal secretions. The best course of action for the physician is to explain the situation and reassure her that she does not have myiasis.

Thank you to Blaine Mathison for helping me accurately describe the flies in this case!