Book excerpt: They live in clothes, on hair, on skin, they live under the skin, in guts, in blood. They're parasites, and they're really into us. But what are these small, squirmy, highly successful organisms? How did they evolve to live inside other organisms, to consume, sicken, and even kill them? Readers will enter the engrossing inner world of bugs, worms, and microbes, explore their riveting life cycles, and discover how these tiny creatures topple civilizations and ruin lives. Readers will learn how to avoid infection or infestation, and what to do if parasites have let themselves in.