A disease or disorder is “rare” if only a limited percentage of the general population is affected.

The definition used by the U.S. Food and Drug Administration (FDA) today is that any disease affecting fewer than 200,000 Americans is considered rare. Several other countries and the European Union have their own definitions of rare diseases, which are similar. In Europe a “rare” disease is one affecting less than 5 in 10,000 people.
For an individual disease these ratios may seem insignificant, but assembled they stand for 30 million people in the USA and almost 35 million people in Europe.
More than 600 million people worldwide suffer from rare diseases.
Because “neglected disease” patients are a minority in industrialized countries, there is a lack of public awareness. Diseases like tuberculosis or malaria are rare diseases in industrial countries but a major global health burden. Neglected diseases are common, communicable diseases that mainly affect patients living in emerging countries. Because they are not a public health priority in the industrialized countries, little research and drug development is performed on these diseases.



