AIDS we're - most of these diseases - we are down from the peak. We're down about 40 per cent from the peak and if we got the right vaccines, which are at the early stage of discovering, then the numbers would come down very dramatically. So that's why we talk about it as an emergency.

Does the e-mail say it's about 'enlargement' - that might be spam.

There's life and death in every email.

There are several hundred people who stayed in the Ebola-affected countries and continued to do the work, put themselves at great risk because medical workers are the most likely to be infected because they're helping out when the person's health is deteriorating, including quite a bit of bleeding as they're getting very, very sick.

The phenomenal generosity of the United States in its aid budget towards health issues is the best in the world. You can look at that broadly, you can look at it in terms of HIV, the PEPFAR money which came together in a Republican administration with bipartisan support.

I do think this next century, hopefully, will be about a more global view. Where you don't just think, 'Yes, my country is doing well,' but you think about the world at large.

We all have the chance to create a world where extreme poverty is the exception rather than the rule.