An epidemic occurs when the number of cases of illness is higher than what is considered normal within a specific region. The term epidemic is used to describe excessive illness within a town, region, or country. Pandemics are epidemics on a much larger scale. The term pandemic describes an epidemic with wide international geographical reach. Pandemics typically include a large number of cases. Although often used to describe widespread outbreaks of infectious disease, the term pandemic has also been used to report high rates of chronic illness. Obesity, a chronic illness in North America, has been called a pandemic. The H1N1 influenza virus and human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) are examples of pandemics of infectious viruses.

Depending on their severity, pandemics have the potential to ...