I am not a very welcoming host. I don't relish the thought of entertaining those that wish to feast or fornicate in, or on, my person. However I realize that for all my pompous self-awareness, I am simply an ecosystem.

There could even be greeblies living in the glands of my eyelashes. The thought is horrific. However, while Demodex brevis feeds off dead skin cells on my face, a place they also use for mating, I take some comfort in the fact they don't defecate there. Thank heaven for small mercies.

Parasites have been in the news a lot of late. Several children in outback Australia have been killed by a brain-eating parasite for which medical experts say treatment is "usually ineffective". That's the least reassuring medical phrase there is.

In America a tapeworm larvae was found happily domiciled in a man's brain, while another man, in a terrifying twist of biology, got cancer from one. Sort of. He developed multiple tumors caused by the worm. The problem is that scientists aren't entirely sure what caused the worm to cause the tumors.

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They theorise that modern pollutants means that parasites may be mutating in terrifying new ways. Let's hope we're not at the forefront of some kind of new plague caused by mutating parasites, because ordinary parasites are scary enough.

Even as I type this, I am a home to creatures currently doing all the things that creatures do. As little as 10% of the living cells that make up our bodies are actually human. That means we are 90% "other".

Of course, most of the 500 forms of bacteria we house do pay their way, helping to protect us from disease, digest our food, or synthesise vitamins. It's the freeloaders and the wreckers that are a concern.

It's not just the thought of a living thing inhabiting me that causes anxiety. There's also the wide array of exciting new ways to be infested: amoebas that enter through the nasal cavity and eat the brain, blood-drinking worms that infiltrate the lymph nodes, small parasitic fish that really do swim up, and lodge themselves in, people's urethras.

Personally I'm more worried about changing climate increasing the range of such entities as the Bot-fly. It sounds like some kind of electronic nano-bug, but it's a particularly clever parasitic predator.

They capture mosquitoes, lay eggs on them, and release them so that the mosquito then distributes the fly's eggs as it bites unsuspecting mammals, including people. The eggs become larvae, and the maggot lives inside you, eventually burrowing its way out. Hopefully.

It could be worse. We could be victims of Cymothoa exigua. Known as the tongue-eating louse, it does just as its name implies. Swimming through the gills of fish, the female attaches herself to the fish's tongue, sucks the blood from it, causing it to atrophy and die, and simply replaces it. The fish then continues to live with a parasite functioning as its tongue.

It adds a whole new meaning to the question: "cat got your tongue?" No. A crustacean killed it in order to replace it and live inside my face. How did that even happen as an evolutionary trait? Just wait till some body-modification aficionado hears about it and tries to do it.

Clearly we can't trust parasites to operate within our own limits of taste or even believability. If they want to give you cancer, be your tongue, or live happily in your eyelashes they will, and there doesn't appear much we can do about it. So don't worry. Sleep tight. Don't let the bedbugs bite.

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