A pandemic is an infectious disease affecting the majority of the population of a large region. When people think of a pandemic, they may think of previous flu pandemics, such as the
1918 flu (also known as "
Spanish flu") or the Hong Kong flu of 1968-1969. A pandemic can also be defined as an infectious disease that is an epidemic at the same time in many parts of the world.
According to the World Health Organization, a pandemic can start when three conditions have been met. The three conditions are:
- The emergence of a disease new to the population
- The agent infects humans, causing serious illness
- The agent spreads easily and sustainably among humans.
A disease or condition is not a pandemic specifically because it kills a large number of people. For example, cancer is responsible for a large number of deaths. But the deaths and disabilities due to cancer are not considered a pandemic because the condition is not infectious.
(Click Pandemic Flu for more information about a specific pandemic.)