“An important and deeply researched book by Theresa MacPhail, a medical anthropologist who memorably portrays the human face of disease . . . In Ms. MacPhail’s analysis, allergy is not only the evil twin of immunity, but also the unexpected dark side of material progress, which has made us unhealthy in ways that we struggle in vain to cure. The author doesn’t have an easy fix for the allergy crisis, but her compassionate insights into the problem make for engrossing reading.”—The Wall Street Journal