Case of the Week 58

The following tiny organisms (10 microns in length) were identified from skin scrapings in a patient with possible scabies. Identification? (CLICK ON IMAGES TO ENLARGE)

Answer to Case 58

I think Ian said it best with the following:
"DEMODEX!!! follicle mite"

This was a tricky case since the follicle mite is rarely seen outside of its habitat of skin hair follicles and their associated sebaceous glands. However, it has a very classic appearance, so once you've seen one, you'll should be able to identify others in the future.

Demodex folliculorum and Demodex brevis are the most common species found on humans. They are a common finding on human skin - espectially on the face - and rarely cause any symptoms. Infestation increases as people age, with as many as 95% of people > 70 years old carrying these mites. If you'd like to see more of these mites, try plucking out one of your eyebrow hairs and looking at it under the microscope.

"The Maggots in Your Mushrooms" - NYTimes

Sometimes, we at Creepy Dreadful Wonderful Parasites think it is better not to know what's in your food:

Click Here for the New York Times Article

Case of the Week 56

The following microscopic organisms were identified in water from a large African lake. They measure between 100-150 microns in length. Many of the residents who use this lake for bathing and drinking have enlarged abdomens. Identification?

Answer to Case 56

Great answers to this week's case! All were correct:

"I think these itchy creatures are Schistosome cercaria - probably S. mansoni based on the [presumably] hepatomegalic abdomens of local bathers"

"I agree - they are the cercariae of S. mansoni (transmitted by the Biomphlaria Spp snail. "

Thank you to everyone who wrote in - both online and off.
These are indeed cercariae of Schistosoma spp. With the history I gave, you are correct in assuming that these belong to S. mansoni. However, it is important to remember that S. haematobium is also present in many parts of Africa. To my knowledge, you can not tell the cercariae of different species apart morphologically at this level.

The CDC has a nice map showing the distribution of S. haematobium (aka urinary schistosomiasis), S. mansoni (aka African hepatic/intestinal schistosomiasis), and where they overlap:
Click here for CDC Map

You'll notice from the map that much of Africa's population is at risk for schistosomiasis.