Worst Pandemics in History in the Last 100 Years

There have been a lot of deadly infectious diseases throughout history, and illnesses like malaria, tuberculosis, influenza, and smallpox have killed hundreds upon thousands over time, ever since humanity’s hunter-gatherer days.

But the shift to agriculture, towns, and cities, made it possible for these illnesses to spread far and wide and become epidemics. However, the very worst case for any disease is when it becomes a pandemic. Unfortunately, with trade and travel, there have been quite a few pandemics across human history.

What is a pandemic?

An epidemic is when a disease rapidly spreads to a large number of people inside a country (or any other given area) in just a short period of time.

A pandemic is when it spreads beyond just a country’s borders. It usually affects people on multiple continents or even worldwide, and a much larger number of people are infected.

However, any communicable diseases that recur yearly or seasonally (like winter colds or seasonal flu) aren’t counted as pandemics. Nonetheless, the history of pandemics in the world is one that is long and deadly.

Here are 10 of the worst pandemics in human history:

1. Antonine Plague

The Antonine Plague (165 to 180 AD) took place during the time of the Ancient Roman Empire. It was a pandemic that spread across the empire – from Gaul (present-day France) to the city of Seleucia (now known as Baghdad).

It’s not known what the disease was, but from descriptions of the symptoms from historical sources that included fever and skin eruption or rashes, scholars suspect that it was either smallpox or measles [1].

Whatever it might have been, it was likely spread by Roman troops who were returning from campaigns in the Near East.

In either case, if it were smallpox or measles, it would be one of the few known cases of those diseases being spread so far and wide, as through history there have been more localized outbreaks and epidemics [2][3] [4]

Outbreak	Number of Deaths	Population lost
Antonine Plague	5–10 million	3–6% of Global population, 25–33% of Roman population

2. Plague Pandemics

The plague is an infectious disease caused by the Y. pestis bacteria. It is spread by small mammals and the fleas that live on them. It has been around for centuries and has caused a number of outbreaks throughout history.

In total, there are three kinds of plague (all caused by the same bacteria) – bubonic, pneumonic, and septicemic, though the most widespread has been the bubonic type.

While some have been small outbreaks or local epidemics, most of them have since been classified as part of one of the three great world pandemics that started in 541, 1346, and 1855. [5]

Outbreak	Number of Deaths	Population lost
Plague of Justinian (541–549) (also called the First plague pandemic)	15–100 million	25–60% of Eurasia's population
Second plague pandemic (starting with the Black Death) (1346–1700s)	75–200 million	30–60% of the European population
Third plague pandemic (1855–1960)	12–15 million	Unknown

3. Cholera Pandemics

Cholera is a disease caused by strains of the bacterium Vibrio cholerae. It’s spread through food or water that is contaminated by fecal matter, which makes it possible for the disease to quickly travel over long distances.

It has been the cause of seven major pandemics throughout history, the last ending in the 1970s. Since then, there have been smaller outbreaks usually after the war, civil unrest, or natural disaster, when food and water become contaminated due to crowded living conditions, and resources are scarce. [6]

Outbreak	Spread	Number of Deaths
First cholera pandemic (1817–1824)	Asia, Europe	100,000+
Second cholera pandemic (1826–1837)	Asia, Europe, North America	100,000+
Third cholera pandemic (1846–1860)	Worldwide	1 million+
Fourth cholera pandemic (1863–1875)	Middle East	600,000
Fifth cholera pandemic (1881–1896)	Asia, Africa, Europe, South America	298,600
Sixth cholera pandemic (1899–1923)	Europe, Asia, Africa	800,000+
Seventh cholera pandemic (1961–1975/ongoing)	Worldwide	Unknown

4. Influenza Pandemics

Commonly known as the “flu”, influenza is a highly contagious disease caused by several related viruses. It attacks the respiratory system, and its effects can range from mild to severe.

Some types of influenza are endemic (or come from) humans, but these types are often not as severe as those that come from other animal species (like pigs or chickens).

There have been six influenza pandemics in the last 150 years alone, and of these, the 1918 flu pandemic (also known as the “Spanish flu”) was the most severe. [7]

Outbreak	Type of Influenza Virus	Number of Deaths
1889–90 flu pandemic	H3N8 or H2N2	1 million
Spanish flu (1918–20)	H1N1	17–100 million
Asian flu (1957–1958)	H2N2	1–4 million
Hong Kong flu (1968–69)	H3N2	1–4 million
Russian flu (1977–79)	H1N1	700,000
Swine flu (2009–10)	H1N1/09	151,700–575,400

5. HIV/AIDS

This condition is one that affects the immune system, and increases the risk of developing other serious infections. It is known as AIDS (or “acquired immunodeficiency syndrome”) caused by HIV (the “human immunodeficiency virus”).

It was first identified in 1981, and for decades the disease had no cure, and spread across the world through unprotected sex, contaminated blood transfusions or needles, and from mother to child during pregnancy. It has infected millions of people and is still ongoing.

However, there is a silver lining, as new antiviral treatments have made AIDS a more manageable chronic health condition. [8]

Outbreak	Number of Confirmed Cases	Number of Deaths
HIV/AIDS pandemic (1981–present)	55.9 million–100 million	35 million+ (as of 2020)

6. SARS

This pandemic involved a respiratory disease known as Severe Acute Respiratory Syndrome (SARS). The disease was caused by a type of virus known as the “severe acute respiratory syndrome coronavirus” (SARS-CoV). The virus was spread through respiratory droplets.

The outbreak first started in China on 16 November 2002, and from there, it spread to 30 countries around the world. It lasted about 18 months before it slowly diminished, and by May 2004, no cases were being reported. [9]

Outbreak	Number of Confirmed Cases	Number of Deaths
SARS pandemic (2002–2004)	8,096	774

7. MERS

Another viral respiratory infection caused by a coronavirus is the Middle East Respiratory Syndrome (MERS). The virus responsible is known as Middle East Respiratory Syndrome-related coronavirus (MERS-CoV).

While the virus is believed to have originated in bats, humans began to be infected from contact with camels. It also spread through contact with an infected person.

While cases of MERS have been seen worldwide since the initial outbreak in 2012 (classifying it as a pandemic), it is uncommon outside of hospitals making both confirmed cases and deaths quite low in number. [10]

Outbreak	Number of Confirmed Cases	Number of Deaths
Middle East respiratory syndrome (MERS) (2012–present)	2574 cases (as of March 2021)	885

8. Ebola

Ebola, also known as Ebola virus disease (EVD), is a type of viral hemorrhagic fever caused by ebolaviruses. It was first identified in 1976 in Sudan and the Democratic Republic of the Congo at a village near the Ebola River.

Since then, there have been numerous outbreaks across sub-Saharan Africa. However, the only one that spread throughout West Africa and even crossed borders (making it a pandemic) lasted from December 2013 to January 2016. [11]

Outbreak	Number of Confirmed Cases	Number of Deaths
Western African Ebola virus (2013–2016)	28,646	11,323

9. Zika

Zika (also often known as Zika fever, or the Zika virus disease) is an infectious disease caused by the Zika virus. The virus is spread by mosquito bites, sexual transmission, and blood transfusions and is especially harmful to pregnant women and their babies.

In other adults, most cases resemble a mild fever or show no symptoms. The virus was first identified in 1947, and since then there have been a few outbreaks in tropical Africa and in some areas of Southeast Asia.

However, in early 2015, there was an outbreak of Zika fever in Brazil that spread to other parts of South and North America and eventually affected several islands in the Pacific and Southeast Asia. This pandemic ended in November 2016. [12]

Outbreak	Number of Confirmed Cases	Number of Deaths
Zika virus (2015–16)	711,381	53

10. COVID-19

COVID-19 is a type of viral respiratory infection caused by a coronavirus (known as SARS-CoV-2). Cases were first reported in Wuhan in China in December 2019, and since then it has spread around the world, becoming one of the deadliest pandemics in history.

It is mainly transmitted through respiratory droplets, though there is also evidence that it is airborne. As of yet, there are no specific vaccines or medicines for COVID-19. However, we do have vaccines and some specific drug treatments to manage the symptoms and eventually help slow down the spread of the virus. [12]

Outbreak	Number of Confirmed Cases	Number of Deaths
COVID-19 pandemic (2019-present)	139 million+ (as of April 2021)	3 million+ (as of April 2021)

Most of these pandemics have not only led to a significant loss of life, but also led to social and economic disruption. Since one of the measures to deal with such widespread diseases is social distancing, it often affects public health systems and can lead to shortages in food and other supplies.

We can see that while modern outbreaks could affect a hundred thousand people before scientists find ways to slow its spread, once upon a time, such pandemics only faded by wiping out a significant part of the population. This kind of upheaval can end up changing the course of history.

While talking about past pandemics, we can look at our past and try to learn from it. Over time, we can see how humans have learned to manage some of these diseases and prepare for emergencies like the one we are facing right now.

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