a disease is considered as rare disease if
Rare disease In the United States, the Rare Diseases Act of 2002 defines rare disease strictly according to prevalence, specifically "any disease or condition that affects fewer than 200,000 people in the United States",[3] or about 1 in 1,500 people. This definition is essentially the same as that of the Orphan Drug Act of 1983, a federal law that was written to encourage research into rare diseases and possible cures.
Hand, foot, and mouth disease HFMD occurs in all areas of the world.[14] It often occurs in small outbreaks in nursery schools or kindergartens.[1] Large outbreaks have been occurring in Asia since 1997.[14] It usually occurs during the spring, summer, and fall months.[14] Typically it occurs in children less than five years old, but can occasionally occur in adults.[1][10] HFMD should not be confused with foot-and-mouth disease (also known as hoof-and-mouth disease) which mostly affects livestock.[15]