Monday, June 28, 2021

Case of the Week 644

This week's case is from Blaine Mathison and Marc Couturier at ARUP Laboratories. They partnered with Techcyte to validate an exciting new system that uses artificial intelligence to identify parasites on digitally-scanned slides (see their recent article). 

Here is a case in which the following objects from a trichrome-stained stool specimen were identified by AI for the technologist's review. They measure approximately 8 to 9 micrometers in diameter. Identification?

Sunday, June 27, 2021

Answer to Case 644

 Answer to the Parasite Case of the Week 644: Cyclospora cayetanensis oocysts on trichrome stain. Additional confirmatory testing (e.g., modified acid fast, UV autofluorescence) is recommended for confirmation. As I mentioned previously, the image from this case was the display screen from the Techcyte AI analysis of a digitally-scanned trichrome-stained slide. You can see that the digital algorithm did an excellent job identifying objects of interest and displaying them to the technologist for review. Use of AI platforms is the future of clinical parasitology, as it drastically reduces the time that technologists have to spend screening negative slides and increases sensitivity for detecting positive cases. Most parasitology labs have an extremely low positive rate for O&P testing - often 95% or more are negative. So a technology that allows our highly trained microscopists to quickly rule out negatives and focus on the positives allows for much better use of their skills, and generally increases job satisfaction! Thanks again to Blaine and Marc for donating this case.

Monday, June 21, 2021

Case of the Week 643

 This week's case is one I've previously shown before, but from many years ago. It's so cool looking that I thought it was worth showing again. The following object was found in a iodine-stained stool concentrate by Florida Fan. Any thoughts on what it is?

Sunday, June 20, 2021

Answer to Case 643

 Answer to the Parasite Case of the Week 643: Not a parasite; plant material. 

As mentioned by Idzi, Bernardino, and Phil G-J, this beautiful structure is a peltate trichome, possibly from an olive (Olea) leaf. Bernardino Rocha provided a great link to this open access article and the photos look just like what we are seeing. 

To obtain further insight, I contacted our knowledgeable botanist reader, Dr. Mary Parker, and was pleased to hear that she agrees with our assessment! She commented that this structure is definitely a peltate trichome and could quite possibly be from the lower epidermis of a leaf of an olive tree. The trichome could have been a contaminant of olives or olive products (e.g., preserved olives, tapenade, unfiltered olive oil) and thus ingested to end up in our specimen. She also mentioned that herbs like mint have glandular peltate hairs on their leaves, but that there are usually fewer of the radiating head cells; therefore, Olea is a more likely source. She provided this striking photo of the lower epidermis of an ash leaf with a trichome. You can also see the guard cells of the epidermis - something we have featured before on this blog (Case of the Week 534 and answer)

We get to see so many fascinating things as parasitologists, and while it's not necessary for us to always know exactly what we're looking at, it's really fun when we can make an identification like this. Thanks again to our faithful contributor, Florida Fan, for donating this case.

Monday, June 7, 2021

Case of the Week 642

It's time for our monthly case from Idzi Potters and the Institute of Tropical Medicine, Antwerp. As always, Idzi has a great case for us - courtesy of Anna Rosanas and Pieter Guetens from ITM's Malariology Department: a patient with extensive recent travel - leaving Belgium to trek across rural areas of Peru, Niger, Mali, and finally the Philippines. He didn't take any malaria prophylaxis while traveling and now presents with fever and general malaise after being home for 3 weeks. The following are thick and thin Giemsa-stained blood films from this patient (pH 8.0). The percent parasitemia was calculated at 1%. Identification?

Sunday, June 6, 2021

Answer to Case 642

Answer to the Parasite Case of the Week 642: Plasmodium sp. infection with relatively high (1%) parasitemia; differential diagnosis includes mixed P. falciparum/P. malariae infection and P. knowlesi infection. Recommend nucleic acid amplification testing for definitive identification.

PCR testing confirmed that this was P. knowlesi infection!

This interesting case highlights the difficulty in diagnosing P. knowlesi infection, given that many of its key morphologic features in humans overlap with those of P. falciparum and P. malariae. Like P. falciparum, high parasitemias may be observed, and thin delicate rings - occasionally with double chromatin dots ("headphone" forms) and applique forms - may be seen. Conversely, all stages of P. knowlesi are commonly seen in peripheral blood, unlike most cases of P. falciparum, so that late stage trophozoites and schizonts are also seen. Many of these later stage forms resemble those of P. malariae, such as "band form" late stage trophozoites. Of note, P. malariae does not reach high levels of parasitemia (1% would be unexpectedly high).

Given this complexity, PCR confirmation is important for understanding the nature of infection and guiding therapy.

Tuesday, June 1, 2021

Case of the Week 641

This week's case was generously donated by Dr. Alexander Fenwick and includes some beautiful images. 

The following objects were seen in a sputum specimen from a patient living in Eastern Kentucky. This patient was receiving corticosteroid therapy for poorly-controlled COPD. Identification?

Gram stain (10x and 100x magnification)

Wet mount: