An epidemic is a widespread occurrence of a disease at a particular time. There are a couple of reasons that every disease doesn’t turn into a epidemic. These are: Epidemics occur only with communicable diseases. Not all diseases are communicable. read more
The disease type as well as available national and international aid all determine this. For Example, Smallpox, regardless of where it occurs is an epidemic due to its high mortality rate whereas necrotizing fasciitis is only epidemic in 2nd and 3rd world countries where medical assistance is nearly non-existent. read more
Introduction into a novel setting; Changes in host susceptibility to the infectious agent; An epidemic disease is not required to be contagious, and the term has been applied to West Nile fever and the obesity epidemic (e.g. by the World Health Organisation), among others. read more