WARNING: If you are creeped out by the thought of creepy crawlies living on or in your body, best hit the Back button and not continue reading.
Still with me? Okay, then, any oogies from here on out are your own responsibility.
Most people reading this board, I think, will not be surprised to read about demodex folliculorum, which is a mite that lives in and around the roots of eyelashes and nearby facial hairs — and not just in humans, either. In addition, the older you are, the more likely you are to have them:
They’re apparently usually harmless, but an out-of-control infestation, evidently in conjunction with another condition, can lead to problems including hair loss and other infections. Generally speaking, though, it’s not a health risk for most people, and the mites just sit there, eating dead skin and other secretions. Good pictures here.
So here’s my question:
How do they get from person to person?
According to that last link, one female mite “may lay up to 25 eggs in a single follicle,” but that doesn’t explain how a tiny little critter that, according to the link in the quote box, moves only one centimeter per hour can get from one person to another. I’ve looked around on the web, but haven’t been able to fill in this gap in their life cycle.
I can hypothesize three reasonable possibilities:
They’re passed from mother to infant, either in utero (which seems extraordinarily unlikely) or during birth (if there are mites living in the pubic hairs). I don’t favor this explanation, largely because of the quote-boxed fact that the older you are, the more likely you are to have them. So it seems more probable that they’re spread physically.
They require close physical contact, i.e. crawling from face to face while you’re sleeping next to somebody. Also unlikely, in my mind; it seems silly to identify “butterfly kisses” or “rubbing your face in Fido’s fuzzy tummy” as a vector for infection. It just sounds too rare to be exploitable by an organism.
Which leads me to:
Airborne eggs. The mite lays eggs in the eyelash, and our blinking dislodges some and sends them wafting off like dust. I know, I know, ewww; this would mean, naturally, that for every egg that lands close enough to a follicle or eyelash to successfully hatch, we have to be breathing in thousands of the things. But then, cleaning crap out of the air in front of our eyeballs is part of the function of the lashes, so it makes sense that a creature would evolve to take advantage of this. As gross as it might seem to be breathing in all these arachnid eggs, we take in a much larger volume of other people’s dead skin with every breath, so this doesn’t really bother me.
So which is it? How does this tiny little beastie get from person to person?
Well, oddly enough my good old copy of Harwood and James’ Entomology in Human and Animal Health ( 7th edition ), doesn’t go into the vector biology of Demodex either.
However I think Gravity has a good part of the answer. Facial contact ( mostly, but conceivably body contact period )would be another. I sincerely doubt both infant transmission ( asidew from bodily contact ) or an airborne route. Interestingly H&J say that the proportion of infested population may reach 100% in the elderly and that jibes with what I was taught. According to my Medical Entomology professor way back when, in 20 years of teaching Med Ent labs, which include self-checking for Desmodex, he’d run across a grand total of ONE person that didn’t have them. This among a pool of people that were mostly in their twenties.
I can proudly say I have them :D. If you have access to a microscope, they’re not that hard to self-diagnos - You just need to pretty firmly scrape part of your face with the edge of a slide.
If you’re buying a set for long term use don’t go for the nonstick. So far no one has made a non-stick coating that lasts. My preferences differ but in your case I’d get the stainless and add any particular non-stick pieces you want.
Nonstick parasites? Doesn’t that kind of defeat the purpose?
Re close physical contact: Have towels and pillows been around long enough for a creature like this to evolve to exploit the vector? Does that also mean that, say, for example, women in burqas (to pull a hypothetical example out of thin air) are less likely to have this parasite, since they come into close physical proximity with so few people, and their skin is largely protected from contact?
Sure this is a WAG, but one I’m willing to lay money on:
Hands!
That’s the main vector for the cold virus. And unlike a cold, where people are taught that they’re supposed to use a tissue and wash their hands often lest they infect others; I’d think people would be more likely to rub their eyes and not even think about using a tissue or washing their hands in order to prevent spreading eyelash mites.
Hey, that’s a pretty good guess, actually. The mites live in follicles; there are hairs on the backs of hands and knuckles; even if the environment isn’t ideal they might still hang on long enough to be transferred from face to hand to hand to face, at least long enough for a gravid female to get a foothold (or whatever type of hold the little critters have). Makes sense. Thanks, that’s an excellent theory.
I guess I’m just surprised that there isn’t more solid information. Seems like somebody would be able to pull out some research, but even Tamerlane’s hefty tome is silent on the subject. Kind of odd…
Nonstick parasites? Doesn’t that kind of defeat the purpose? 