Major outbreaks and pandemics over time: a simplified chronological review and their classification according to their severity

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Major outbreaks and pandemics over time: a simplified chronological review and their classification according to their severity

What is it about?

The Covid-19 outbreak that we are currently experiencing is not the first one to appear in the world, far from it!

We are going to take a look at the epidemic and pandemics that have occurred in the past and classify them according to their severity.


What is an epidemic?

The occurrence of a disease on a large scale in a particular area is called an epicemic. If it spreads to a larger area, it is called a pandemic. These diseases are said to be transmissible if they are spread within the population by a micro-organism such as a bacterium or a virus.

An epidemic is declared when the disease spreads to a large area, infecting a large number of people in a relatively large geographic area. When efforts to contain the disease become insufficient, an outbreak occurs.

It spreads to many people within a particular community or locality.

What is a pandemic?

Pandemics are the final stage in the progression of a disease and refer to an international disease that gets out of control. Pandemics occur when an outbreak spreads to multiple countries. Covid-19 is an excellent example of a pandemic, as the disease began at a modest level (a few cases and then an outbreak in Wuhan), before progressing to epidemic and pandemic levels within months. While pandemics can eventually be controlled over time, they require considerable effort to contain.

These outbreaks and pandemics occur and spread when the newly emerged microbe reaches a naïve population with no natural or vaccine immunity. This is typically the case with Covid 19. On the other hand, when the population is immunized (collective immunity), the germ no longer circulates and the endemic disease progressively dies out, circulating only at a low level, as in the case of measles, tuberculosis, leprosy or even smallpox, which, thanks to vaccination, no longer exists on the surface of the globe.

The different epidemics

While there is evidence that major outbreaks, particularly of plague, occurred during the Late Neolithic and Early Bronze Age (4800 – 3700 BC), decimating entire populations, only those that occurred in the present era will be discussed here.

The plagues

Plagues that are not plagues! They were given the name “plague” meaning ” fléau ” in Latin. Now, the term plague is reserved for the disease given by a bacterium “Yersinia pestis“.

The plague of Athens 430 BC

This outbreak that took place during the Peloponnesian War lasted for 5 years and ravaged the Athenian people. It was not a “real plague” because it was not caused by the bacterium Yersinia pestis.

The Plague of Antoninus, which killed more than 5 million people in the Roman Empire during the years 165-180, was most likely caused by viruses such as smallpox or rubella. It killed more than a third of the Roman population and decimated the Empire’s army. By weakening the economy and military supremacy, it is very likely to have been the cause of the decline of the Roman Empire.

The real plagues

Justinian’s plague or first pandemic

During the years 541-542 it devastated between 30 and 50 million lives in the Byzantine Empire under the reign of Justinian the Great. The Empire collapsed with his death. This first pandemic shows some resurgence until the middle of the 8th century.

The Black Death: 1346-1353 or second pandemic.

It originated in China and traveled along the Silk Road to Asia Minor and Europe. It raged in Europe for five years, from 1347 to 1351, and devastated more than 50% of the population of the European continent at that time. It is reported that more than 200 million people died from this disease. It was the deadliest pandemic in human history.

Smallpox epidemic in Japan: 735-737

The Japanese smallpox outbreak, which occurred from 735-737, affected most of Japan, killing approximately 1 million people, or one-third of the Japanese population at the time with significant social, economic, and religious repercussions throughout the country.

The epidemics of the New World

They invaded the new world as soon as it was discovered in 1492.

Smallpox: 1520

Unknown to the new world it was introduced by the conquerors in 1520 and killed 56 million people (¼ to ½ of the population of central Mexico), causing the fall of the Aztec Empire.

The cocoliztli outbreak 1545-1548

In the Aztec language this term means, “pest, plague…”

It was most certainly a viral hemorrhagic fever that killed 10 to 12 million people in the space of 3 years, eliminating 80% of the population of New Spain (proportionally, an even more catastrophic toll than the Black Death in Europe).

The European plagues of the seventeenth and eighteenth centuries were resurgences of the second Black Death pandemic: Plague of Lyon (1628), Plague of Milan (1629-1631), Plague of London (1655), Plague of Marseille (1720-1723), Russian Plague (1770) and others.

These plagues, which ended towards the end of the 18th century, caused about 3.6 million deaths.

Cholera 1817-1923

It is estimated that 1 million people died of cholera during the 6 pandemics that took place successively from 1817 to 1923. We are currently in the 7th pandemic which started in 1961.

The 3rd plague pandemic: 1877-1945

Started in Yunan, China in 1855, it invaded the whole world, killing 12 million people in India and China alone.


From the 19th century onwards, influenza began to spread thanks to rapid urbanization and industrialization.

The Russian flu, 1889-1890 (H2N2 influenza virus) killed nearly one million people

The Spanish flu, 1918-1920 (H1N1 influenza virus) occurred in 2 waves, the second being much more deadly than the first. The mortality rate has been revised upwards since it is now estimated that nearly 50 million people died from this flu. Despite the immense shock it caused in people’s minds, it quickly disappeared to the point of being partially forgotten.

Asian flu, 1957-1958 (influenza virus H2N2). It mainly ravaged Asia and the United States, killing nearly one million people.

The Hong Kong flu, 1968-1970 (influenza virus H3N2): 1 million deaths

AIDS 1981-

It is the oldest pandemic of the modern era. The HIV virus is responsible for the death of almost 35 million people.

The pandemics of the new millennium

SARS (Sars-cov 1 virus) 2002-2004, 770 deaths on the Asian continent

EBOLA virus killed about 11,000 people during the years 2014-2016 in West African countries

   MERS (MERS-Cov virus) has killed 850 people since the year 2012.

 COVID-19. The current pandemic is the deadliest pandemic of the 21st century. It is also caused by a coronavirus. It has affected almost every country in the world. Although it was identified in China in November 2019, it spread to all of Europe during March and April 2020. As of June 30, 2021, it had killed nearly 3.9 million people.

Classification according to the number of deaths:

1- Black Death (1347-1351), 200 million

2- Smallpox (1520), 56 million

3- Spanish flu (1918-1919), 40-50 million

4- Justinian Plague (541-542) 30-50 million

5- AIDS (1981-) 25-35 million

6- 3rd Plague pandemic (1855) 12 million

7- Antonine Plague (165-180) 5 million

8- Covid-19 (2019-) 3.9 million deaths

9- Resurgence of the Black Death XVII and XVIII, 3, 6 million

10- Asian flu 1957-58) 1,1 million

But this ranking based only on the number of deaths is biased, given that total populations have varied greatly over time. A more interesting ranking can be based on other criteria, even if the number of deaths is the main indicator of the overall impact of the pandemic on society. Infection and mortality rates can be combined, as both are indicative of the overall strength of each specific disease. Perhaps most importantly, the social, economic, and political impact of each pandemic can be added to this, as all of these factors are known to impede recovery efforts in substantial ways.

The ranking then becomes the following

1- The Black Death


3- The Spanish Flu

4- Justinian’s Plague

5- Antonine Plague

6- Asian flu

7- Cholera 1852

8- Russian flu

9- The Hong Kong flu

10 – Cholera 1899

It is not surprising to note that the Black Death remains the greatest pandemic disaster of all times.

As for AIDS, considering the environmental, social, economic and political conditions, it is exceptionally serious because of its sexual transmission, its long incubation period and then its slow evolution, which requires an immunosuppression of the organism, a treatment that is very difficult to find, going from a monotherapy to a tritherapy with numerous side effects, the absence of immunity and vaccine…

Then came the Spanish flu, which was superimposed on the facts of the 14-18 war, adding 40 to 50 million deaths to the 20 million caused by the war itself.


If we divide the appearance of outbreaks and pandemics into two, taking the nineteenth century as a starting point, the first part consists of cholera, plague, etc., which accompany wars and other events related to poor hygiene, while the second part is represented rather by influenza that would be the result of rapid urbanization and industrialization.

It is therefore clear that unhygienic environments and pollution are at the origin of the rapid spread of pandemics. In addition, the development of transportation and information technology has made the world a global village. It is obvious that the spread of contagious diseases is inevitable. However, human beings should adopt a positive attitude by considering that pandemics may come and go but humanity has always stayed alive!


Vallarasi S, S. Regi, Tracking the chronology of epidemics and pandemics, J. Nat. Remed., 21, 2020, 100-105.

Larry Slawson, The 10 worst pandemics in history





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