This is the shocking story of the longest running battle of all time - man vs parasite. From fleas, ticks, lice and bedbugs to worms, mites, leeches and maggots, Marrin explains what parasites are, how they invade human bodies and what their effects are, both good and bad. Kids will learn that, at their best, parasites have saved limbs and lives. At their worst, they've been responsible for the deaths of billions of people and changed the course of human history. The creepy-crawlies are richly illustrated and photographed in full-colour throughout.