List of epidemics and pandemics

This is a list of the largest known epidemics and pandemics caused by an infectious disease in humans. Widespread non-communicable diseases such as cardiovascular disease and cancer are not included. An epidemic is the rapid spread of disease to a large number of people in a given population within a short period of time; in meningococcal infections, an attack rate in excess of 15 cases per 100,000 people for two consecutive weeks is considered an epidemic. Due to the long time spans, the first plague pandemic (6th century – 8th century) and the second plague pandemic (14th century – early 19th century) are shown by individual outbreaks, such as the Plague of Justinian (first pandemic) and the Black Death (second pandemic).

Infectious diseases with high prevalence are listed separately (sometimes in addition to their epidemics), such as malaria, which may have killed 50–60 million people.

Ongoing epidemics and pandemics are in boldface. For a given epidemic or pandemic, the average of its estimated death toll range is used for ranking. If the death toll averages of two or more epidemics or pandemics are equal, then the smaller the range, the higher the rank. For the historical records of major changes in the world population, see world population.

There have been various major infectious diseases with high prevalence worldwide, but they are currently not listed in the above table as epidemics/pandemics due to the lack of definite data, such as time span and death toll.