This is Your Brain on Parasites

by Kathleen McAuliffe

c.2016, Houghton Mifflin Harcourt; $27.00 / $39.00 Canada; 288 pages

You didn't get much sleep last night. You were too busy checking windows.

The blame for that lies squarely on that creepy show you've been watching on TV; all you could think about was what it would be like to be eaten by zombies. But read the new book This is Your Brain on Parasites by Kathleen McAuliffe, and you'll see that the real danger isn't outside your window.

It's inside your skin.

As an adult human being, you are in control of your life. You're rational, decisive, and interpretive - or are you? Could it be possible that your decisions, food choices, sex life, and personality are driven by something you picked up from your last vacation, your local grocery store, or your cat?

Yes, says science writer McAuliffe, it's not only possible - it's probable.

Parasites, which include viruses and bacteria, have been around for about as long as humans have, and some of them are beneficial. You literally could not live without the flora in your gut, for instance.

As for the nasty ones, McAuliffe says, "virtually every aspect of the human body's design bears witness to their presence and to the age-old struggle to thwart what those parasites can do."

By definition, a parasite hitches a free ride from a host, and then rudely takes advantage of the host's reluctant hospitality by stealing nourishment. And that would be bad enough, if that was all they did. As scientists have recently learned, though, some parasites also manipulate hosts for further gain, nicer living quarters, or for reproduction. It happens to mice and rats, birds, ants, snails, beetles, cats and dogs --- and maybe you.

Some parasites, says McAuliffe, may "alter human odor to enhance our attractiveness to mosquitoes." Others, like the Black Death, can outright kill us. To a scientist, your personal parasites identify you. Parasites can paralyze you, make you sniffly, and they can disgust you (thus, saving your life). They may help in choosing a mate.

And, yes, they might eat your brain.

Is it possible to read This is Your Brain on Parasites without scratching? I don't think so. This book is creepy like that, but it's also absolutely mesmerizing.

With a surprisingly light tone that sometimes edges toward humor, author Kathleen McAuliffe manages to do several things at once in this book. She takes readers, first of all, inside laboratories, animal burrows, and hospital rooms to show us how parasites invade pretty much everything living. That will sometimes make your flesh crawl, but it also serves to make parasites awfully interesting too. Finally, in a big picture view of what those hangers-on have done to other creatures, McAuliffe poses the question: what have they done to us?

Try not to think about that too much before you've read this book, and then try not to let it bother you. There is little you can do about unwanted hitchhikers anyway, so read This is Your Brain on Parasites and just relax. Seriously, don't let it eat at you.