The Theories of Epidemic, Pandemic and Endemic

by Bharatbiotech
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Infectious diseases are spreading around the world faster than ever. As diseases spread, epidemic, pandemic and endemic are the frequent words we get to hear about the disease. But these words do not mean the same. So what is the difference between a pandemic, an endemic and an epidemic?

Let us look at each of these terms and understand what they mean –

All three words have Greek roots, and the one they have in common is demos (the people). Let’s sort out epi- from pan- and en-.

Epidemic (epi – “upon or above”)

The term epidemic is used when a contagious disease, mainly of viral origin, reaches a significant number of people in a given city, region or country and for a certain period of time.


A few well-known epidemics include Zika virus, Chikungunya, Dengue fever, Typhoid, SARS, the Ebola epidemic in West Africa, which killed 11,300 people between 2013 and 2016.

Pandemic (pan – ”all”)

We speak of a pandemic when an epidemic extends beyond national borders, across a continent or even around the world. It causes a serious illness that is passed easily from one person to another, so it spreads across a wide geographic area, affecting many people.

In history, there have been a number of devastating pandemics – the black death/the plague, which killed more than 75 million people way back in 1350, the most deadly Spanish flu, smallpox and, currently, AIDS, tuberculosis, Ebola, swine flu, bird flu etc., can be considered as pandemic viral infections, since they affect the entire world.

On March 11, 2020 coronavirus was declared a pandemic by the World Health Organization.
Map showing Coronavirus (COVID-19) Pandemic 2020

Endemic(en – “in, within”)

An endemic is the usual persistence of an infectious and contagious disease in a given region and affects a large part of the population. They remain at a steady state, but do not disappear from a population.

Chickenpox is classed as an endemic as it occurs at a high but predictable rate among youngsters.


This term is used when more cases of a disease than expected are recorded in one area. An outbreak could even be a single case of a contagious disease new to a community or one not seen for a long time.


Now that we have understood the terms related to the spread of a disease, let us look at Coronaviruses in detail and understand more about the disease in our next blog.  Read here>

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1 comment

nidhin July 4, 2020 - 7:42 am

Hi Team Bharath Biotech

Heard that your company is run behind to find the vaccine for covid-19. Good Luck. We Indians moreover humans are keeping hope on you people. Good Luck. .


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