What is the difference between an outbreak, epidemic, and a pandemic? Outbreak describes the sudden rise in the incidence of a disease, especially a harmful one. An outbreak is characterized by a disease's bypassing of measures to control it. An epidemic is a disease that affects many people at the same time, such as the flu. The US Centers for Disease Control and Prevention's official definition of epidemic is: 'The occurrence of more cases of disease than expected in a given area or among a specific group of people over a particular period of time'. A pandemic is the worldwide spread of a new disease.

What is an epidemic? An epidemic occurs when an infectious disease spreads rapidly to many people. In 2003, the severe acute respiratory syndrome (SARS) epidemic took the lives of nearly 800 people.

What is a pandemic? A pandemic is a global disease outbreak. Spanish influenza killed 40-50 million people in 1918.