What is the greatest problem facing the world today? Islamic terrorism? Nuclear proliferation? There’s a good case to be made that the gravest problem of our day is the spread of AIDS. In terms of sheer numbers, the AIDS catastrophe dwarfs the Holocaust (although of course, intentional extermination is very different from disease). About 25 million people have already died of AIDS. Most of the 40 million people who now carry the disease are doomed. Now, in an important and disturbing piece in Foreign Affairs Nicholas Eberstadt warns that the epidemic may be about to take yet another quantum leap, as it spreads out of Africa and moves deeply into Russia, China, and India.