Difference between Epidemic and Pandemic

Published on April 18, 2016

A lot of people are confused by the term ‘epidemic’ as opposed to ‘pandemic’, both used by epidemiologists to describe the extent of a disease’s effect on the affected population within a specific period of time.


Epidemic vs Pandemic
Healthcare workers wearing personal protective equipment during the Ebola epidemic in West Africa.

An epidemic is the sudden increase in the number of cases of a particular disease within a population group. This is usually abrupt and unexpected, and must be above the normal incidence trend in that area. It may be restricted to one location only, but it doesn’t necessarily mean that it has to be a city or a country. An epidemic can occur in any population group within the scope of any number of locations like a village, a province, a country or even an entire continent.

A notable example of an epidemic is the Ebola Virus Disease in West Africa. Starting in 2013 and continuing to 2016, this disease has been declared an epidemic affecting more than 25,000 people with an estimated 11,000 deaths. It is currently the best known epidemic around the globe. A smaller epidemic was also declared in Madagascar in 2014 due to bubonic plague affecting 119 people with an estimated 40 deaths.

Contrary to popular belief, the term epidemic is not only used in infectious diseases as it can also be used in non-infectious ones like diabetes and cancer. In 1997, the World Health Organization declared obesity as a global epidemic since it is a major concern of all countries worldwide. In the 1940s, leukemia was also declared an epidemic in Hiroshima following the atomic bomb attack in the area during World War 2.

A hospital ward during the 1918 – 1919 Spanish Flu pandemic.

A pandemic is an epidemic that has spread to other countries or continents. It is basically an epidemic that worsened and progressed to affect large scale populations.

However, unlike the term ‘epidemic’, ‘pandemic’ is only used in cases of contagious or infectious diseases. The term is used to describe an epidemic that was not successfully controlled or resolved and continued to affect other population groups.

An example would be the 1918 – 1919 Spanish Flu pandemic. It affected more than 500 million people worldwide with an estimated 100 million deaths. All countries around the globe were hit by the pandemic, including the remote Pacific islands and the Arctic. Only one area was declared unaffected, namely the isolated island of Marajo in Brazil.

Epidemic vs Pandemic

What’s the difference between epidemic and pandemic? They both refer to a sudden increase of disease cases in a period of time but they differ in the scope of area concerned. An epidemic is an outbreak of disease that occurs within a concentrated group of population in a particular location, while a pandemic is a large scale epidemic that affects multiple groups of populations across different locations.

The easiest way to remember the difference between the two is through understanding disease progression. Keep in mind that an epidemic is a precursor to a pandemic.

Caparison Chart

Affects a particular population groupAffects large scale groups of people
Specific to one city, region or countryCovers wide geographical area and multiple locations
May be caused by any disease, both infectious and non-infectious illnessesUsually caused by a new type of highly transmissible virus