endemic - epidemic - pandemic

• endemic - regularly found among particular people or in a certain area
• epidemic - an outbreak of a contagious disease that spreads rapidly and widely
• pandemic - an epidemic over a wide geographic area and affecting a large proportion of the population

When is a Disease Termed Pandemic?

It is when the number of people affected by the disease does not constraint to a locality. (A relatively huge number of populations will be affected)It could be across states and countries as well. A perfect example of a pandemic disease will be AIDS. This has become a global threat since eighties