“Any disease!” she’d cry, and then parse the adjectives. “ ‘Contagious’ isn’t really a medical term, so ignore that—they just tossed in the kitchen sink there—but you really need to understand the distinction between ‘infectious’ and ‘communicable.’ ” All communicable diseases were infectious, but some infectious diseases were not communicable. Communicable meant a person could give it to another person. You could get Lyme disease, for instance, but you couldn’t give it to somebody else. Communicable diseases were the diseases that created
