In 1996 I had just turned thirty. If you had told me at the time that parasites were about to become an integral part of my life for years to come, I would have said, “Oh, look at the time! I’ve got to go feed my hyrax!” and headed for the nearest restroom to scrub my hands.

But it would have been true. I just had finished my first book, and I was wondering what to write next. I had a couple vague ideas I bounced around with my agent over lunch. How about an exploration of the intersection of biology and philosophy? A blank look. How about a book about parasites? Boom: my agent sat up.

That decision led me to