By Bjørn Lomborg
In rich countries, the biggest causes of death are strokes, heart attacks and cancer, accounting for more than two-thirds of all deaths. But for the poorer world, people often assume that infectious diseases like diarrhea, tuberculosis, AIDS, malaria, measles and tetanus are the biggest killers. That is no longer true. While they are still substantial threats, broader availability of medication and vaccines along with higher living standards has caused such communicable diseases to drop dramatically to below 9 million deaths each year.