Answer to Case 581

Answer to Parasite Case of the Week 581: Demodex folliculorum, the human follicle mite.

Demodex are fascinating arthropods that live in our follicles and sebaceous glands. There are 2 species found in humans: D. folliculorum and the shorter D. brevis. Many of us have them - especially as we get older - and they are mostly commensals, not causing any symptoms. However, they may cause rosacea and blepharitis (inflammation of the eyelids) in some individuals.

As with all arachnids, they have 8 legs as nymphs and adults, and 6 legs as larvae. Adults have a genital opening right below the legs, which allow them to be distinguished from nymphs:

The video from this case shows how many mites can live in a single follicle. Kosta Y. Mumcuoglu noted that there are at least 6 specimens of D. folliculorum present, with at least two of them embedded in the follicle. By viewing the video on full screen mode, I think there may even be more - up to 8 based on the movement I see within the follicle. Wow!

Thanks again to Theodore Trejo for donating this very nice case. I'll close with the fun poem from Old One:

DEMODEX

This micromite is called Demodex

It can be found in many acarology text

Not designed to move very far

8 stubby legs and the shape of a cigar

It dwells in the follicles of old ones brow

And if you didn’t know this by now

Usually nonpathogenic but occasionally is thought

To cause rosacea however this theory is fraught

with controversy. We have only to thank Herr Dr. Jake Henie

Who discovered this mini monster dwelling within Thee