The market focuses on profit and not care being provided. Businesses have no vested interest in making people healthier, only making money. These go against individuals in terms of their needs for protecting their health, because it is more beneficial to them for you to be worse so often they work in conflict with your best interests. Neglected tropical diseases are diseases affecting a developing nation or nations that are neglected in terms of research funding and care because they are not profitable, as many of those affected can not afford to purchase the necessary medication, as the population affected is generally poorer and from developing "tropical" countries. Examples of NTDs are hookworm infection, dengue fever, river blindness, and leprosy. The 90-10 gap is that 90% of the disease burden in the world receives 10% of research funding. A privileged lifestyle drug that is not essential but profitable, like Viagra or Rogaine. An example of a lost cost NTD drug that is not profitable is Ivermectin, which treats for parasites for 10 cents.