Our world is filled with diseases, viruses, and other nasty things with the sole purpose of organic destruction. Even as the human body evolves to fight them, they evolve too. Most of these diseases are spread through human contact. Now, what kind of human can have no contact with others and therefore not spread disease? The answer is, of course, a dead one, so my solution is simple: we (humanely) kill all sick people. This will, I'm sure, completely eradicate disease. It might also prove helpful in preventing any overpopulation issues we may have in the future. Think how great society would be if we didn't have to worry about diseases; we could evolve infinitely further physically, we would never have to worry about family and friends becoming sick (what's there to worry about for a dead person?), and only those who are physically perfect would survive. In conclusion, to make our world a cleaner and safer place, we must simply eradicate the weak. What could go wrong?