Saturday, January 21, 2017

Case of the Week 431

This week's case is an arthropod which was found on a sandy beach in South America. It is approximately 1 mm in greatest dimension.


Saturday, January 14, 2017

Case of the Week 430

This week's case is from an elderly institutionalized patient with diffuse thickened skin on her arms and back. A crust from skin was submitted for examination, and scrapings showed the following:

Many were hard to photograph because they kept moving! Identification?

Friday, January 13, 2017

Answer to Case 430

Answer: Sarcoptes scabei, the scabies or human itch mite. The presence of thick skin crusts is consistent with crusted or 'Norwegian' scabies.

This case demonstrates adult mites (with 8 legs) and nymphs and larvae (with 6 legs). Eggs with clearly-visible internal larvae are also seen:

Here are some fun facts about Sarcoptes scabei. They are arachnids, rather than insects (related to ticks and spiders). Also they undergo incomplete metamorphosis between life cycle stages (i.e. they are hemimetabolus). That means that the immature forms such as larvae and nymphs look very similar to the adults. That is quite different from holometabolus arthropods where the larvae look completely different from the adult (a good example is the flea which has a worm-like larval stage).

Here is a fun little poem from Florida Fan to go with this case:

Itchy, itchy little buggy.

Wherever cramped and unsanitary
You spread, from one fellow inmate than another,
You itch, I scratch then the bacteria follow to bother.
From the spaces between the knuckles,
To where there is a skin fold you dwell
For the poor souls, you terrorize you inflict just hell.
Itchy, itchy little buggy,
Sarcoptes scabiei you're not funny.

Saturday, January 7, 2017

Case of the Week 429

This week's case was generously donated by Dan Rhoads at the Cleveland Clinic. The following video and images were taken from a corneal culture. What are the objects seen here?

Pay particular attention to the object denoted by the arrows and arrow head:

If you watch the video closely, you can see some motion in the object outlined by the arrows above (enlarge the video to view using your full screen):

Friday, January 6, 2017

Answer to Case 429

Answer: Acanthamoeba sp.
Shown here is a characteristic double-walled cyst and 2 less-easily visualized trophozoites. You can also see the background bacteria (Escherichia coli) which had been plated on the agar as a food source for the amebae. Florida Fan suggested that some creative editing would allow the trophozoite to be more easily seen, so here is my best shot:
Now that you know what to look for, I would encourage you to go back and look at the video again. If you watch closely, you can see subtle movements inside of the trophozoite with opening and closing of the contractile vacuole. Geeky parasite fun!

Tuesday, January 3, 2017

Case of the Week 428

Happy New Years! I have 2 announcements to make with this post. First, we will be "opening" 2017 with a beautiful case from Florida Fan (see below). Second, I want to announce that I have a new website:  This website will serve as a repository for the cases that I post on my blog (in an easy-to-search A through Z format). The website also contains a flashcards feature where you can test your knowledge of common and uncommon parasites. I will continue to populate the image bank and flashcards as I post new cases, so I \encourage you to bookmark this page and check back often.

So now, on to the case:
This object was identified in a concentrate stool specimen. The photograph was taken at 400x, and the object measures just over 150 micrometers in length. No further history is available. Identification?

Sunday, January 1, 2017

Answer to Case 428

Answer: Fasciola hepatica/Fasciolopsis buski egg.

As some of you pointed out, the characteristic features of this egg are:
1. It's large size
2. The presence of an operculum
3. The thin clear wall and internal undifferentiated embryo

I love this particular egg because it is 'opening' for the new year!

Tuesday, December 27, 2016

Case of the Week 427

Welcome back for the last case of 2016!

I thought I would close out the year with an old favorite. The case and beautiful images are donated from George at MSKCC. The specimen is concentrated stool from a young child.

Identification of the 2 worms shown here?

Monday, December 26, 2016

Answer to Case 427

Answer: Enterobius vermicularis (pinworm) male and female adults

The adult worms are easily identified by their prominent lateral alae:

The male and female can be further differentiated by looking at their tails; males have a coiled tail while females have a straight tail.

This case is unusual for a couple of reasons; first, we don't typically see adult pinworms in stool specimens (they are more commonly [and ideally] detected using tape preparations), and second, it is even less common to see male pinworms in clinical specimens. The females are more commonly seen because they are the ones that leave their safe residence in the large intestine/cecum to travel nightly to the perianal folds to lay their eggs. The males typically remain behind. The fact that we see both male and female pinworms in stool makes me wonder if this was a particularly heavy infection.

Thank you again to George from MSKCC for donating this interesting case!

Sunday, December 18, 2016

Case of the Week 426

Happy Holidays to all of my readers! Can anyone tell me who the happy couple is below the mistletoe?