Disease, like poverty, is not distributed uniformly among people and countries. In the developing world, the chance of dying is almost 30 times greater for an infant, at least 40 times greater for a child and more than a 1000 times greater for a pregnant woman compared to their counterparts living in an industrialized nation.

Infectious diseases account for approximately one half of all deaths in the tropical areas of the world. Nearly all of these deaths occur in children under the age of five. Those infectious diseases that are primarily found in the developing world or profoundly impact the health of people living in the tropics are frequently referred to as tropical diseases.