What is a pandemic or an epidemic?

See below: Epidemic - a cluster of new cases of a disease in a specific geographic area over a certain period of time. E.G. Meningitis epidemic in U.S. Pandemic - a cluster of new cases of a disease in specific geographic areas across the world or a large region of the world over a specific period in time. - e.g. Aids or 1918 influenza.

Epidemic/ Pandemic: An epidemic occurs when there are new cases of an infectious disease in a population over a period of time with greater incident rate than expected. An epidemic can grow into a pandemic when that infectious diseases affects an even larger area/population over a certain period of time (such as multiple continents or worldwide). There is currently an Ebola Zaire epidemic in West Africa.