I first became a vegetarian when I was nine, in response to an argument made by a radical babysitter. My great change - which lasted a couple of weeks - was based on the very simple instinct that it's wrong to kill animals for food.
People are beginning to understand there is nothing in the world so remote that it can't impact you as a person. It's not just diseases. Economists are now beginning to say if we are going to have good markets in Africa, we're going to have to have healthy people in Africa.