The biggest public health challenge is rebuilding health systems. In other words if you look at cholera or maternal mortality or tuberculosis in Haiti they're major problems in Haiti but the biggest problem is rebuilding systems.

We've taken on the major health problems of the poorest - tuberculosis maternal mortality AIDS malaria - in four countries. We've scored some victories in the sense that we've cured or treated thousands and changed the discourse about what is possible.

The answer to old age is to keep one's mind busy and to go on with one's life as if it were interminable. I always admired Chekhov for building a new house when he was dying of tuberculosis.