World's Deadliest Diseases in the History

1. Bubonic Plague

The bubonic plague is a serious infectious disease that is caused by the bacillus Yersinia pestis. Also known as “The Black Death,” and “The Pestilence,” it has been around for centuries, with the very first instance being the Plague of Justinian that took place between 541–549 AD.  

The Y. pestis bacteria spreads through infected fleas or small mammals, such as rodents, and is passed on to humans who are bitten or scratched.  It is found all over the world, but since the bacteria was discovered in 1894, scientists soon developed ways of treating and preventing its spread, and it is now curable in most cases with things like antibiotics! 

The Black Death (1346–1353) led to people developing public health measures like isolating sick people, quarantines, and doctors wearing protective clothing!   

Here are the details of the plague outbreaks throughout history: [1]


When and Where

Number of Deaths

First Plague Pandemic

Started with the Plague of Justinian (541–549 AD) and lasted till the 8th century in Asia, Africa, and Europe.

15–100 million

Second Plague Pandemic

Started with the Black Death (1346 to 1353) and lasted until the 1700s in Europe and Northern Africa.

75–200 million

Third Plague Pandemic

Numerous occurrences starting in 1855 spread all over the world until 1912. Most of the outbreaks were in China and India.

12–15 million

2. Influenza

Influenza (also called the flu) is a highly contagious disease that attacks the respiratory system and is caused by a number of types of influenza viruses. While it’s possible that there have been influenza outbreaks since 6,000 BC, the first written record of an influenza epidemic, and the respiratory illness we know today, was in 1510.  

While there are types of influenza that come from humans, influenza pandemics usually take place when a new strain of the virus is transmitted to humans from another animal species, especially animals that we eat (like pigs, chickens, or ducks).  

Symptoms of the flu range from mild to severe and usually include fever, a runny nose, sore throat, muscle pain, headache, coughing, and tiredness. 

These are some of the worst influenza pandemics throughout history: [2]


Type of Virus

Number of Deaths

1510 influenza pandemic


Around 1% of those infected

1557–1559 influenza pandemic (Asia, Africa, Europe, Americas)



1732–1733 Thirteen Colonies influenza epidemic (North America)



1847–1848 influenza epidemic (Worldwide)



1889–90 flu pandemic (Worldwide)

H3N8 or H2N2

1 million

1918–20 influenza pandemic: “Spanish flu” (Worldwide)


17–100 million

1957–1958 influenza pandemic: “Asian flu” (Worldwide)


1–4 million

Hong Kong flu (Worldwide)


1–4 million

1977 Russian flu (Worldwide)



2009 swine flu pandemic (Worldwide)



2015 Indian swine flu outbreak (India)



Typical annual seasonal flu*

Various types

290,000–650,000 per year

 *Not a pandemic, but included for comparison purposes.

3. Cholera

This deadly disease is an infection of the small intestine that’s caused by strains of the bacterium Vibrio cholerae, though some types are more severe than others. Usually, its symptoms include vomiting, muscle cramps, severe watery diarrhea leading to dehydration, and ultimately, death. 

Cholera has been around for centuries (likely originating in the Indian subcontinent) and has caused seven major pandemics starting in 1817 in the Bengal region of India. People can contract the bacteria through unsafe water that has been contaminated with human waste and the bacteria. Unfortunately, cholera still leads to the deaths of 50,000 to 120,000 people every year. 

An outbreak of cholera in 1854 in London led Dr. John Snow to recognize the importance of clean water to public health, and to the study of epidemiology, i.e the study of how infectious diseases spread.  

Here are the major cholera outbreaks throughout history: [3]


When and Where

Number of Deaths

First cholera pandemic

1817–1824, in Asia, Europe


Second cholera pandemic

1826–1837, in Asia, Europe, North America


Third cholera pandemic

1846–1860, Worldwide

1 million+

Fourth cholera pandemic

1863–1875, in Middle East


Fifth cholera pandemic

1881–1896, in Asia, Africa, Europe, South America


Sixth cholera pandemic

1899–1923, in Europe, Asia, Africa


Egypt cholera epidemic



Seventh cholera pandemic

1961–1975, Worldwide


Bangladesh cholera epidemic

1991, in Bangladesh


Latin America cholera epidemic

1991–1993, in Peru, Chile, Bolivia, Ecuador, Colombia, Mexico, El Salvador, Guatemala


Zimbabwean cholera outbreak



Haiti cholera outbreak



Yemen cholera outbreak

2016–2021, in Yemen

3,886 (as of 30 November 2019)

4. Smallpox

Luckily, we don’t hear about smallpox these days, as it has been completely eradicated due to vaccination. But once, it was one of the deadliest diseases to humans! It was caused by the Variola virus, and symptoms included fever, vomiting, skin rashes, and blisters.  

While we don’t know where it originated from, and it has been around for centuries, the first widespread outbreaks took place in 18th century Europe.  

Though people in ancient China and India tried to use some methods to inoculate against smallpox (like by rubbing infected scabs or fluid into scratches made on a healthy patient in the hopes of building immunity!) it was only in 1798 that Edward Jenner developed the first version of what we now call a vaccine. 

Smallpox was spread between people or via contaminated objects (killing around 500 million people in just the 20th century alone), and the development of this smallpox vaccine really helped to fight the disease.  

These are some of the major smallpox pandemics throughout history: [4]


Number of Deaths

Percentage of the Population

735–737 Japanese smallpox epidemic

2 million

About 1⁄3 of Japanese population

1520 Mexico smallpox epidemic

5–8 million

40% of population

1561 Chile smallpox epidem


20–25% of native population

1707–1709 Iceland smallpox epidemic


36% of population

1738–1739 North Carolina smallpox epidemic



1775–1782 North American smallpox epidemic


30% of population

1789–1790 New South Wales smallpox epidemic


50–70% of native population

1828–1829 New South Wales smallpox epidemic



1837 Great Plains smallpox epidemic



1862 Pacific Northwest smallpox epidemic



1870–1875 Europe smallpox epidemic



1974 smallpox epidemic of India



5. Typhus

Also known as typhus fever, this disease is actually a group of infectious diseases that include epidemic typhus, scrub typhus, and murine typhus, all of which are caused by bacteria spread by lice,  fleas, and mites. Its symptoms include fever, headache, and a rash.  

While it's likely that typhus has been around for ages, the first described cases were in 1489 AD. However, there have been many outbreaks throughout history, usually starting in places with poor sanitary conditions and overcrowding. Luckily, it is now rare and can be treated with antibiotics like doxycycline.  

Some of the worst outbreaks of typhus were: [5]


Number of Deaths

1489 Spain typhus epidemic


1812 Russia Typhus epidemic


1817–1819 Ireland typhus epidemic


1847 North American typhus epidemic


1918–1922 Russia typhus epidemic

2–3 million


First identified in 1981, HIV, which is the virus that causes AIDS (or acquired immunodeficiency syndrome), might have come from African chimpanzees and was transferred to humans in the early 20th century.  

It was first detected in the Democratic Republic of the Congo in 1976, and for decades the disease had no cure. But now, new treatments have made HIV a far more manageable chronic health condition. In fact, annual deaths from HIV/AIDS dropped from 2.2 million to 1.6 million globally, and two people have even been cured of HIV as of early 2020!  [7]


Number of Confirmed Cases

Number of Deaths

HIV/AIDS pandemic, 1981–present (Worldwide)


35 million+ (as of 2020)

7. Dengue fever

Dengue is a tropical disease that is caused by the dengue virus, which is spread by mosquitoes – especially the Aedes aegypti species. It causes symptoms like high fever, headache, vomiting, muscle and joint pains, and a skin rash, but in some cases, it leads to severe fever, hemorrhagic bleeding, and death.  

Luckily, there is now a vaccine for dengue, as well as antiviral drugs being developed to treat it!  

While there might have been cases of dengue fever since the 5th century AD, the earliest report of an epidemic is from 1779 when swept across Southeast Asia, Africa, and North America. Since then, until the end of the 20th century, cases were rare. But they have become more frequent due to ecological disruption. 

These are some of the major dengue reports throughout history: [8]


Number of Confirmed Cases

Number of Deaths

1778 Spain dengue fever outbreak



2000 Central America dengue epidemic



2004-06 dengue outbreak in Singapore, India, Indonesia, Pakistan, and the Philippines

Around 20,000

Around 1,800

2007 dengue fever epidemic in Puerto Rico, Dominican Republic, Mexico



2008 Brazil dengue epidemic

55,000 +


2010 dengue fever epidemic, worldwide



2011 dengue outbreak in Pakistan



2017 dengue outbreak in Sri Lanka



2019–20 dengue fever epidemic



8. Malaria

Like dengue, malaria is also a mosquito-borne infectious disease spread by the Anopheles mosquito. It’s caused by the Malaria parasite, and its symptoms include fever, tiredness, vomiting, and headaches and in severe cases, they can also include yellow skin, seizures, coma, or death. 

In some cases, if the disease isn’t properly treated, the person can have reoccurring symptoms months or even years later! 

Nowadays, there are several medications to prevent malaria, as well as antimalarial medications to treat it. In 2020, a vaccine was even developed, and it can reduce the risk of malaria by about 40%! 

Some of the worst outbreaks of malaria were: [10]


Number of Deaths

1600–1650 South America malaria epidemic


1829–1833 Pacific Northwest malaria epidemic


1829 Netherlands malaria epidemic


1906 malaria outbreak in Ceylon (now called Sri Lanka)


1942–1944 Egypt malaria epidemic


2006 India malaria outbreak


9. Coronavirus

COVID-19 is caused by a coronavirus (SARS-CoV-2), and was first reported in Wuhan, the capital of China’s Hubei province, in Dec 2019, and is thought to have originated in animals, likely bats. Since then, it has spread around the world.  

Coronaviruses are a large group of viruses that often cause respiratory infections, with symptoms ranging from mild to severe, including fever, tiredness, a dry cough, and a loss of sensation of smell. The virus that causes COVID-19 is mainly transmitted through droplets generated when an infected person coughs, sneezes, or exhales. 

While there is no specific treatment for COVID-19, there are many ways to manage it, like oxygen support, antivirals, and most importantly, vaccines! [10]


Number of Confirmed Cases

Number of Deaths

COVID-19 pandemic (2019-present)

167 million+ (as of May 2021)

3 million+ (as of May 2021)


So, while there have been many outbreaks of these deadly diseases that have ravaged humanity, we can say that over time, we humans have learned to manage some of these diseases, which of course, is great news for our future! 

Until then, have you considered getting a health insurance to help you out if you ever have to face such an unfortunate situation? Well, here’s something to help you out with that.