10 Deadliest Epidemics in Human History
10 Deadliest Epidemics in Human History

Top 10 Deadliest Epidemics in Human History

Epidemics (roughly translated meaning “Upon People” from ancient Greek epi = “upon/above” and demos = “people”) were historically and are still among the biggest concerns for humanity. The term epidemic describes infectious diseases that are quickly spreading among people of a certain population. If the epidemic spreads to most or all parts of the world, the disease then becomes pandemic. A pandemic can, therefore, be described as an intercontinental, worldwide or global epidemic.

As the ongoing Covid-19 pandemic shows, epidemics tend to now even spread faster in our modern globalized world. In fact, many leading scientists and experts on the topic consider the threat of epidemics the major threat for humanity as a whole, even more so than climate change. Bill Gates, the founder of Microsoft and one of the richest people in the world, is one of them. He has been warning the world of new major disease outbreaks that will spread quickly throughout the world for quite some years now.

But epidemics and pandemics of course have existed long before our modern globalized world. While they may have not spread as quickly, the lack of medical knowledge and efficient measures against them during those times, actually tended to make the epidemics even more deadly as the following list of epidemics will show you. This list of epidemics ranks the deadliest known epidemics in human history by the estimated number of deaths these major global outbreaks caused. Just a heads up: Each one of these epidemics have tragically claimed more than a million lives.



The 10 Deadliest Epidemics in Human History

List of epidemics in known human history, sorted by the number of deaths that the outbreaks caused.

1. Black Death Plague

black death - deadliest epidemics - list of epidemics
Depiction of a 14th Century miniature showing the people of Toumai (modern-day Belgium) burying victims of the Black Death plague

Around 140 million deaths (some estimates go as high as 200 million)

Period: 1346 – 1353 (possibly much longer)
Affected regions: Mostly Europe (almost half of the contemporary European population perished), Middle East & North Africa (around 1/3 of the contemporary Middle Eastern & North African populations perished)

Disease: Bubonic Plague
Caused by: Yersinia Pestis bacteria
Infection through: Oriental rat fleas carrying the bacteria, infecting people through flea bites.

Origin: Oriental rat fleas, which carried the Yersinia Pestis bacteria, originated in Central Asia or East Asia. They then spread to the Crimean Peninsula following the Silk Road. From there on sailors inadvertently brought rats with the infected fleas on ships to Italy. Thus, the bacteria then rapidly spread practically throughout all of Europe with only some notable exceptions (e.g. Milan and the Kingdom of Poland).

2. Spanish Flu

spanish flu - second on the deadliest list of epidemics
American soldiers in Camp Funston (Kansas) suffering from the so-called Spanish Flu in 1918

3. AIDS Pandemic

Image result for aids kills
An “AIDS Kills” graffiti in South Africa, one of the countries hardest hit by the AIDS pandemic

Around 36 million deaths

Period: 1959 – ongoing
Affected regions: Almost all regions of the world, but especially Sub-Saharan Africa.

Disease: Acquired Immune Deficiency Syndrome (AIDS)
Caused by: Human Immunodeficiency Virus (HIV)
Infection through: Mainly through sexual contact with an infected person, but virus can also spread through blood transfusions, hypodermic needles, breastfeeding, and to an unborn child of an infected mother during pregnancy.

Origin: The virus originated in Central Africa, more precisely in what is now the Democratic Republic of the Congo. For as of yet not completely clear reasons the Simian Immunodeficiency Virus (SIV) affecting chimpanzees, gorillas, and other monkeys transferred into humans and mutated into HIV. The virus then quickly spread throughout Sub-Saharan Africa. In the early 1970s, the virus arrived in the USA and from there on spread globally.

READ ALSO: Top 10 Natural Remedy To Lower High Blood Pressure

4. Plague of Justinian

Plague of Justinian Plague of Justinian Attacking the Eastern Roman Byzantine Empire
Depiction of victims of the Plague of Justinian in an unknown city at the Mediterranean Sea

Around 30 million deaths (some estimates go as high as 50 million)

Period: 541 – 542
Affected regions: Byzantine Empire, especially its capital Constantinople (modern-day Istanbul) and practically all regions around the Mediterranean Sea (around 20% of the contemporary world population in total perished)

Disease: Bubonic Plague
Caused by: Yersinia Pestis bacteria
Infection through: Oriental rat fleas carrying the bacteria, infecting people through flea bites.

Origin: Oriental rat fleas, which carried the Yersinia Pestis bacteria, originated in Central Asia or East Asia. The rats with fleas eventually spread to Egypt. From there on sailors inadvertently brought the rats with the infected fleas on ships to Constantinople (modern-day Istanbul). From there on the bacteria then spread throughout the coasts of the Mediterranean Sea. Among the infected was Justinian I., the emperor of the Byzantine Empire at the time. The epidemic was hence named after him (Justinian I. ended up surviving the disease, however).

5. Third Plague Pandemic

Chinese victims of the Third Plague Pandemic, photo taken in 1911

Around 22 million deaths
Period: 1855 – 1960
Affected regions: Primarily China & India, to a lesser degree als much of the entire rest of the world

Disease: Bubonic Plague
Caused by: Yersinia Pestis bacteria
Infection through: Oriental rat fleas carrying the bacteria, infecting people through flea bites.

Origin: Rats from Central Asia, carrying infected fleas, brought the Yersinia Pestis bacteria to the Yunnan Province of China, where the epidemic started around 1855. The epidemic eventually spread to Hong Kong, back then a major trading post for the British Empire. From there on, merchants and sailors inadvertently spread the rats throughout most of the world with constant outbreaks on all continents. As a major trading partner, British-ruled India was especially hard hit by the pandemic as the bacteria spread especially fast throughout the Indian subcontinent. Tens of millions of Indians perished from the Plague. The pandemic lasted more than 100 years until 1960, making it the longest pandemic in recorded history.

6. Cocoliztli Epidemic

Remains of victims of the Cocoliztli Epidemic found in Chalco Valley, Mexico

Around 10 million deaths (around 3/4 of New Spain’s contemporary population)(some estimates go as high as 15 million)

Period: 1545 – 1548
Affected regions: New Spain (modern-day Mexico Guatemala)

Caused by: Unknown
Infection through:

Origin: The origin of the epidemic remains unknown. Some evidence points to the Spanish colonizers who conquered and settled what is now Mexico at the time. Newest DNA studies suggest that they may have inadvertently brought a rare European strain of the Salmonella enterica bacteria to the Americas and infected the native population. The usual Salmonella symptoms do not match the contemporary witness descriptions of the symptoms seen in the Cocoliztli Epidemic, however (Cocoliztli = “disease” in Nahuatl, the native Aztec language). The described symptoms were high fever alongside a black tongue, vertigo, dysentery, chest pains, and severe bleeding from the nose, eyes, and mouth. The origin of the epidemic, therefore, remains largely unproven.

READ ALSO: Top 10 Most Deadly Fruits on Earth 2020

7. Aztec Smallpox Epidemic

Depiction of Spanish colonizers treating ill Aztec people during the Smallpox Epidemic

Around 7 million deaths
Period: 1520 (with constant smaller outbreaks until 1951 all over Latin America)
Affected regions: Aztec Empire (modern-day Mexico)

Disease: Smallpox
Caused by: Variola Major Virus & Variola Minor Virus
Infection through: Infected humans spread the virus through close face-to-face contact by little droplets of bodily fluids that contained the virus.

Origin: Spanish colonizers (“Conquistadores”) led by Hernan Cortes invaded the Aztec Empire in 1519 and in the process inadvertently spread smallpox among the indigenous populations. Unlike the Europeans, the native Aztecs never dealt with smallpox before and therefore had not built up any immunization against the virus. Beginning in May 1520 and lasting until the end of that year, the virus quickly spread throughout the Aztec lands, even killing some notable Aztec leaders including Cuitlahuac, the ruler of the Aztec capital Tenochtitlan (modern-day Mexico City). Even after the Aztec epidemic, the virus later further spread throughout all of the Americas, killing millions of indigenous Americans until 1951, when the virus finally got eradicated.

8. Antonine Plague

Image result for antonine plague
Depiction of Rome during the Antonine Plague

Around 5 million deaths (some estimates go as high as 8 million)

Period: 165 – 180
Affected regions: Roman Empire (especially Rome itself, where 1/3 of the population perished)

DiseaseUnknown (possibly Measles or Smallpox)
Caused by: Unknown
Infection through: Unknown

Origin: The origin of the epidemic and the disease remain largely unknown. Based on the described symptoms of the infected, the epidemic was most likely caused by the measles or smallpox outbreak, which Roman soldiers, merchants or diplomats may have brought to Europe from China, where especially smallpox outbreaks were relatively common. In Europe, both viruses were unknown at the time and the Europeans, therefore, had not formed an immunity against either disease yet. Once the epidemic reached Rome, the most populated city in the world back then, it killed 1/3 of the city’s entire population.

The epidemic lasted for 15 years and spread to almost all parts of the Roman Empire. The outbreak (wrongly called a Plague) is named after Marcus Aurelius, the Roman emperor at the time, whose full name was Marcus Aurelius Antoninus (given by his adoptive father and predecessor Roman emperor Antoninus Pius). Aurelius’ adoptive brother and co-emperor, Lucius Verus, was likely among the infected and died in 169 at the peak of the epidemic in Rome.

9. Asian Flu

Infected children during the Asian Flu in an infirmary in Troy, New York, USA

Around 3 million deaths (some estimates go as high as 4 million)

Period: 1956 – 1958
Affected regions: China, Hong Kong, Singapore, to a lesser degree also USA & Europe

Disease: Influenza (a.k.a. Flu)
Caused by: Influenza A H2N2 Virus
Infection through: Infected humans spread the virus to others by coughing and sneezing.

Origin: The Virus originated in China, where it may have transferred and mutated to humans from ducks. The virus quickly spread to neighboring Hong Kong and to Singapore by sea. The virus also reached Europe and the United States, where it claimed around 70,000 lives. The epidemic was controlled and eventually entirely stopped by the development of an effective vaccine in 1957.

READ ALSO: 10 Most Scary Diseases that Affect Humans

10. Persian Plague

Around 2 million deaths
Period1772 – 1773

Affected regions: Persian Empire (modern-day Iran, Iraq, Bahrain), to a lesser degree, also modern-day Pakistan & India

Disease: Bubonic Plague
Caused by: Yersinia Pestis bacteria
Infection through: Oriental rat fleas carrying the bacteria, infecting people through flea bites.

Origin: The epidemic started in Bagdhad in the winter of 1772. The rats with the infected fleas then quickly spread throughout the Persian Empire and especially along the Persian Gulf coast, eventually reaching Bahrain. In the East, the bacteria reached as far as modern-day Mumbai, India. The epidemic didn’t last long but was extremely mortal with thousands of deaths being recorded per day at the peak of the outbreak. Only imposed quarantine measures in Persia managed to eventually contain the epidemic by the end of 1773.


Here is a quick rundown of the Top 10 Deadliest Epidemics in Human History Ever – 2020.

(as of March 2020)

~ 140 million deaths
~ 50 million deaths
~ 36 million deaths
~ 30 million deaths
~ 22 million deaths
~ 10 million deaths
~ 7 million deaths
~ 5 million deaths
~ 3 million deaths
~ 2 million deaths


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