So the wonderful life cycle of this little bastard starts when microfilariae produced by adult worms get ingested by a fly, where they manage to stay alive and develop through its larval phases and station themselves in the fly's proboscis. Then the parasite is transferred to a human once the fly bites someone. The flies that commonly carry the nematode, the mango fly and deer fly, are also not really upstanding citizens, given that they transfer the parasite by slicing a painful cut in the skin and licking the blood. So thanks for that, mango fly and deer fly. You assholes.
Maybe leave a tip or something for your "blood meal," guys. At least don't leave a goddamn parasitic worm.
Once in a human, the larva parties around in the subcutaneous tissue for awhile until it grows up into a big, evil adult. They then decide to feed on the vitals in various parts of the human body, including the spinal fluid, lungs, and blood. The cycle keeps going when another fly slices you open to drink your infected blood and transfer the microfilariae to someone else.
The loa loa is also commonly known as the "eye worm." You know, because it likes to infect your eye.
These worms range in length from 2 centimeters to a whopping 7 centimeters, which doesn't seem all that bad when compared with, I don't know, the Woolworth Building, but it seems awfully big when it's in your friggin' eye. Infection generally results in pain and cysts and swelling when the worm is elsewhere, and the unpleasant sensation of a worm crawling over your eyeball when it's up in that region. Assuming it wants to hang out somewhere else, it's likely going to be in your joints and cause them to be rather painful. And if it happens to die inside you, the body becomes a waste product and promptly causes abscesses and pus to sprout around its grave. It's kind of like how I imagine Jerry Falwell's cemetery plot looks.
Overall, some 12 million people are affected by loa loa infestation at any time, usually in about 11 nations of Africa. Often the treatment is taken through diethylcarbamazine, and if that sounds like a scary thing it's because it's one of those "side effects include death" compounds. Another option is cocaine. No, really. Apparently the idea is to paralyze them with a solution of coke and then remove them. So now you know for sure, though I'm sure many of you suspected it: Charlie Sheen was swarming with disgusting worms.
Then again, I'm pretty sure there's no real unpleasant way of getting a worm out of your eyeball, since the options seem relegated to a) the worm slithers out over your face or b) the worm makes its way back down into your body and exits some other way. There is of course, another possibility: having a doctor evict the unwanted guest. It's possible to pop a few 10-syllable drug drops onto your peeper and make a little incision and use some forceps to get it out. There's at least one video of the surgical procedure to remove the worm here, though it's kind of telling that it comes with a sidebar of a ton of gross-out stuff. Maybe just a picture from the procedure will be a little more tolerable, since-
Seriously, loa loa, go to hell.