Case of the Week 658

This week's case is a thick blood film from a patient with fever and recent travel to East Africa. Diagnosis? Would you like any additional studies?

Case of the Week 657

This week's case features a Giemsa-stained thin blood film from a patient with recent travel to India. Identification? For a BONUS, can you list the different stages in images 1-4 below?

Answer to Case 657

 Answer to the Parasite Case of the Week 657: Plasmodium vivax

Thanks to all of the great comments on this case! There are so many classic features of P. vivax here, that it makes for a fabulous teaching slide. Florida Fan very nicely outlined all of the diagnostic features along with his thought process for coming to the final identification:

1/ The ring is fairly large, and the infected red cell is larger than the not infected. As such, there is a predilection for reticulocytes. Either P. vivax or P. ovale.

2/ The mature trophozoites are ameboid form, showing them to be highly Vivacious. More than likely P. vivax.

3/ The schizont in the third picture demonstrates more than twelve merozoites, P. ovale does not usually have that many. (on average, 8)

4/ The gametocyte in the fourth picture is not Falciform, it occupies almost the entire red cell. Though there is a little bit of fimbriation, all evidence gathered so far including the geographic area are consistent with an identification of P. vivax.

Here is a composite image of the 4 forms shown in this case:

Case of the Week 656

 It's time for our monthly case with Idzi Potters and the Institute of Tropical Medicine, Antwerp:

The following was seen in a urine sediment from a backpacker returning to Belgium following a 2-month's trip in Northern Senegal. During his travels, he reports being bitten by insects, drinking and eating local foods, and swimming in fresh water lakes. He is asymptomatic, but is concerned that he may has picked up a parasite along the way. 

How would you interpret this finding?

Answer to Case 656

 Answer to the Parasite Case of the Week 656: mite, probable contaminant from the environment. Not likely of human medical significance.

As several readers noted, this mite is not one of the 2 human pathogenic mites, Sarcoptes scabei or Demodex. Instead, it is likely a mite from the environment, such as Dermatophagoides, the dust mite. The presence of many squamous epithelial cells in the background would support this idea:

You can read the following posts for more information for how to differentiate the various mites found in human specimens:

Case of the Week 634: Free-living mite found in stool

Case of the Week 196: Differentiating Sarcoptes scabei from other mites

Case of the Week 601: Key identifying features of Sarcoptes scabei

Case of the Week 655

 This week's case features small (~2 micrometer long), oval-shaped objects seen in a corneal scraping. Thanks to Heather for taking these beautiful images. The stain is strong trichrome (chromotrope 2R method). 

What is the most likely diagnosis?

Answer to Case 655

Answer to the Parasite Case of the Week 655: Microsporidia spores. Nucleic acid amplification/sequencing and/or electron microscopy is required for genus and species level identification.

Microsporidia that are commonly implicated in corneal infection include Vittaforma corneae and Encephalitozoon hellem.

As noted by Dr. Harsha Sheorey, the Ryan’s modified Trichrome stain was created by his friend and colleague, Dr Norbert Ryan. This stain has now become a standard staining technique for these organisms, and what was used in this case. The microsporidia spores stain bright red against a blue background.

 

Case of the Week 654

 This week's case is of a middle-aged man with a painful lesion on the dorsum of his foot. He recently returned from Brazil, during which he swam in the ocean, walked barefoot on the beach, and ate local foods. An excisional biopsy was performed and submitted to the clinical microbiology lab to rule out a possible parasite. The specimen received was an excised ellipse of skin on which there was a central defect measuring ~ 5 mm in diameter:

There was also a separate section of subcutaneous tissue, which contained numerous tan-white ovoid objects:

Here is a close-up of these objects:

To confirm our suspected diagnosis, we serially sectioned the skin and submitted the sections for histopathologic processing. Here are a couple of images from the H&E stained slides (using the 4x and 10x objectives):

Identification?

Answer to Case 654

 Answer to the Parasite Case of the Week 654: Tunga sp. flea

I encourage you to check out the posts in the Comments section by Kosta and Florida Fan who give us an excellent description of the taxonomy, morphology, epidemiology, and clinical presentation of this parasitic flea. 

Here are some of the diagnostic features from this case:

Tunga sp. eggs measuring ~0.6 mm long:

Egg within the body of the flea, along with other characteristic features:

We weren't able to locate the head of the flea, so there is a chance that it is still embedded in the skin of the host. This is not usually of significant concern, however, as the body will eventually extrude the retained flea parts. Occasionally patients will secondary bacterial infection and require antibiotic treatment.

Case of the Week 653

 This week's case was generously donated by Drs. Alex Fenwick and Julie Ribes at the University of Kentucky. The following structure was retrieved from bronchial washings of a patient with end-stage lung disease due to cystic fibrosis.  

The next 2 images show both ends of this object.

Most likely identification?