Case of the Week 813

This week's case was donated by Heather Morris, the parasitology lead in my laboratory. We received the following objects for identification:

What would you like to do next? We typically try at least 2 things to come to a diagnosis. Please share your techniques!

Answer to Case 813

Answer to the Parasite Case of the Week 813: tapeworm proglottids; gross morphology consistent with Taenia species. 

Thank you all for sharing your approaches to providing further work-up and identification! 

Check out the many excellent responses in the comments. Of them, the comments from HCLM fan, Idzi Potters, and Florida Fan most closely mimic our approach:

1. We first closely examine the proglottids using a dissecting microscope to discern if the submitted object is a true tapeworm or some type of worm mimic (e.g., food material, mucus strands). 
2. During examination, we note the size of the object to help narrow the diagnostic possibilities. In this case, the large size is indicative of either Taenia or a fish tape worm such as Dibothriocephalus. 
3. To differentiate between these 2 groups, we look at the length of the proglottids and any external markers such as the laterally-positioned uterine pore or central uterine rosette. As noted by Idzi, this specimen possesses a lateral pore which is consistent with a Taenia species adult. Having proglottids that are longer than they are wide also points us towards a Taenia species.
4. We then manipulate the proglottids to attempt to express eggs from the proglottids and spin down the fluid form the original container.

Here are the eggs from this case - a great example of Taenia sp. eggs!

Since we cannot differentiate the Taenia species by the eggs alone, we will then try to squeeze a proglottid between two glass slides, or between the inverted lid and base of a Petri dish in order to view the internal uterine structures:

Proglottid manipulation is done with extreme caution since the specimen could be T. solium, in which case the eggs could result in cysticercosis if accidentally ingested. 

Like HLCM fan, we avoid India ink injection since it's a challenging technique and often doesn't work when specimens arrive in ethanol or formalin. However, here is a beautiful example by Rachel Voss, MLS(ASCP):

When we are lucky, we get a nice view of our squashed proglottid like the following:

If we are not able to visualize the branches by transilluminating the proglottid, then we usually try to submit the specimen for histologic sectioning. However, as noted by other readers, one can also attempt to clear the specimen using lactophenol or stain it with carmine. 

Once the uterine branches are visualized, we can count the number of primary branches originating from one side of the central uterine stem; >13 = T. saginata or T. suihominis; <13 = T. solium. 

This case contains >13 branches, so this is good news for the patient and family - there is no associated risk of cysticercosis from the eggs shed into the environment from the host. 

Lastly, molecular testing can be used if there is doubt as to the identification; for example, if the proglottids are immature.

Thank you again for sharing your protocols!

Many thanks to Heather and Emily from my lab for sharing these beautiful photographs!

 

Case of the Week 812

This week's case features two ~1 cm long tan-white worms removed from the terminal ileum during routine colonoscopy. What is your identification?

Anterior end:

Posterior end - worm one:

Posterior end - worm two:

Answer to Case 812

Answer to the Parasite Case of the Week 812: Adult hookworms, male and female.

As noted by Idzi Potters and Florida Fan, it's a bit hard to make out the mouth parts from the first photo. However, by focusing up and down on the actual clinical specimen, we were able to confirm that there are 2 pairs of teeth present, consistent with Ancylostoma duodenale. The second image shows the end of the female worm, whereas Idzi notes that the third "gives a nice view of the bursa copulatrix - a specialized organ found in male hookworms, used for sensing and grasping during copulation." The spicules at the end of the male do not appear to be fused, which supports the identification of A. duodenale.

Florida Fan noted that "The images may be sufficient for treatment but for academic purposes they pose a challenge. Would a stool parasitology culture help to identify the species involved?" This is a great question. If eggs are present in the stool, they could be hatched using the Harada Mori or similar culture method, and this would allow them to develop into L1 and eventually L3 larvae. There are some subtle differences between the L3 larvae of the different hookworm species, so it might be possible to differentiate them from the L3 stage alone. However, I'm not sure I would be able to accurately differentiate them. Unfortunately, this is where the life cycle stops for stool culture; we can't rear the larvae into adults, since this requires entry into a suitable host. Thank you for bringing up this option, Florida Fan!

Case of the Week 811

 This week's case was donated by Dr. Francesca (Frankie) Lee. The following images are from Gram-stained and wet prep slides of a BAL from an immunocompromised patient. 

The following growth was also noted on routine aerobic bacterial culture:

What is your diagnosis? Are there any precautions you would institute for the samples in the laboratory?