Eradication is the lowering of an infectious disease's numbers in all those suffering from it in the world's population to zero. (It is sometimes confused with elimination of infectious diseases. Elimination of infectious diseases is a very similar idea. Elimination of infectious diseases is the lowering of an infectious disease's numbers in all those suffering from it in a "local" population to zero.) The only human disease to be eradicated is smallpox. The only animal disease eradicated is rinderpest.