This week's case is generously donated by Dr. Nazia Nagi from Maulana Azad Medical College in New Delhi. The patient is a young, HIV-positive, adult male with diarrhea. The following structures were seen in a wet mount and modified Ziehl-Neelsen stained stool preparations. They measure approximately 35 micrometers long. Identification?
Answer to the Parasitology Case of the Week 720: Cystoisospora belli oocysts
These oocysts are easy to differentiate from Cyclospora and Cryptosporidium oocysts based on their large size and ovoid shape. Thanks again to Dr. Nazia Nagi for donating this classic case!
This week's case is very timely! The following objects were seen on a modified safranin-stained stool specimen. They measure approximately 8 to 10 micrometers in diameter. Identification?
40x objective:
100x objective:
Answer to the Parasite of the Week 719: Cyclospora sp. oocysts.
While Cryptosporidium spp. oocysts have a similar appearance, they are smaller than Cyclospora oocysts, measuring only 4-6 micrometers in diameter.
Note that Cyclospora oocysts do not stain uniformly with either the modified acid fast or modified safranin methods, although there tends to be fewer unstained oocysts with the latter. The microwave modification of the safranin stain will also improve the staining uniformity (see the CDC procedure HERE).
Welcome back to our first case of the month, with a special case from Idzi Potters and the Institute of Tropical Medicine, Antwerp. The following structures were found in a bronchoalveolar lavage from a middle-aged Belgian patient with asthma who presented with increased shortness of breath. He reports no travel out-of-country and works as an administrator at an insurance company. He recently reported an insect infestation in his home.Video credits are for Monique Vatlet (CHU Ambroise Paré, Mons, Belgium).
Answer to the Parasite Case of the Week 718: ciliated epithelial cells; NOT Lophomonas. Many of our readers suspected this case to represent Lophomonas blattarum - a flagellated protozoan parasite of cockroaches - but there is no convincing evidence that Lophomonas is actually a human parasite. Also, there are a number of helpful features that can differentiate ciliated human epithelial cells from L. blattarum:
1. Human ciliate epithelial cells have a well-defined terminal bar with a compact row of short cilia (arrows) rather than the tuft of long flagella possessed by Lophomonas.
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3. The beating motility of ciliated epithelial cells is very rhythmic and non-direction compared with true Lophomonas.
For those of you who are asking "what about the PCR evidence implicating Lophomonas blattarum as a human pathogen in respiratory samples??" Well, a thorough analysis of the PCR primers conducted by my colleague, Dr. Richard Bradbury revealed these primers to show a lot of cross-reactivity, particularly with the oral trichomonads. Therefore, amplification using this PCR in respiratory specimens would not be conclusively supportive of Lophomonas. Again, though, the difference in motility patterns between ciliated human epithelial cells and Lophomonas are really striking, and allows for definitive differentiation in my mind.
This week's classic case was generously provided by Florida Fan. The following was seen in a Giemsa-stained peripheral blood smear. No additional history is available. Diagnosis?
Answer to the Parasite Case of the Week 717: Brugia malayi
This case was a little bit tricky in that the tail didn't show a clear terminal and subterminal nucleus as expected for B. malayi. However, the tail nuclei were separated, there is a long head space, and the sheath stained deep pink with Giemsa (the latter being a 'soft' feature).
To confirm the findings, many of you rightly noted that you would try to get the patient's travel history and also look for other microfilariae in this specimen. B. malayi is restricted to Asia and SE Asia and is a cause of lymphatic filariasis.
Thanks again to Florida Fan for donating this case!
Happy May, everyone! As the first Monday of the month, it's time for our post from Idzi Potters and the Institute of Tropical Medicine, Antwerp. Idzi was recently featured in a great article by the Institute - you should check it out!
This month's case are the following objects seen in 3 different stains from a patient with sudden onset of profuse watery diarrhea and abdominal cramping:
Concentrated wet preparation with Lugol's iodine
Heine stain
Modified acid fast stain
What is your diagnosis?
Answer to the Parasite Case of the Week 716: Cyclospora cayetanensis oocysts
On the wet mount preparation with Lugol's iodine, one can nicely appreciate the spherical oocyst with well-defined outer wall and internal globular bodies. The oocysts are not highlighted by the Heine and trichrome stains (latter not shown), but their presence may be suspected by their negative contour. Confirmation can be made by staining with modified acid fast stain (or modified safranin stain), and by demonstrating autofluorescence with fluorescence microscopy.
It is important to measure the oocysts on the stains above, since cryptosporidium oocysts have a similar appearance. C. cayetanensis oocysts are 8-10 micrometers in diameter, while Cryptosporidium spp. oocysts are 4-5.
