World's Deadliest Diseases That Impacted Human History

Communicable diseases are one of the greatest threats humankind faces. They have existed for ages, wreaking havoc around the world and ravaging human lives. Diseases like smallpox, malaria, plague and Spanish flu are a few examples. 
 

In this article, we will discuss the nine world’s deadliest diseases that took millions of lives across the globe, some of which are still prevalent.

List of World’s Deadliest Diseases that Impacted Human History

1. Bubonic Plague

   The bubonic plague, known as the “Black Death” and “The Pestilence,” is one of the most dangerous diseases in history. The bite of a flea infected with Yersinia pestis (a bacterium) causes plague. Fleas usually live on tiny animals like marmots, rats and squirrels. 
    

   The first instance of bubonic plague took place between 541-549 AD. Between 1346 and 1353, the disease took over most of the Mediterranean and Europe. It wiped out more than 60% of Europe’s population. 
    

   Headache, chills, swollen and painful lymph nodes and lung infections are some symptoms of bubonic plague. Plague can now be cured in most cases with antibiotics.
    

   Outbreak	Occurrence	Number of deaths
   First Plague Outbreak	541-549 AD in Africa, Asia and Europe	15-100 million
   Second Plague Outbreak	1346-1353 in Europe and Northern Africa	75-200 million
   Third Plague Outbreak	1855-1912, all over the world but mainly in India and China	12-15 million




2. Spanish Flu (Influenza)

   Variants of Influenza viruses cause influenza or flu. The disease affects the respiratory system and is highly contagious. The first known occurrence of the influenza epidemic goes back to 1510. However, the flu pandemic that occurred between 1918 and 1920 was most severe, which was caused by the H1N1 virus. It is popularly known as the “Spanish Flu” or “The Great Influenza Epidemic.” 
    

   While humans are host to many Influenza viruses, a pandemic occurs only when a new strain is transmitted to humans from animals like ducks, pigs and chickens. Fever, sore throat, runny nose, headache and watery red eyes are a few symptoms of Influenza. 
    

   Type of virus	Occurrence	Number of deaths
   Unknown	1510	Around 1% of the infected people
   Unknown	1557-1559 in Asia, Africa, Americas and Europe	Unknown
   Unknown	1732–1733 in North America	Unknown
   Unknown	1847–1848, worldwide	Unknown
   H3N8 or H2N2	1889–90 flu pandemic, worldwide	1 million
   H1N1	1918–20 “Spanish flu”, worldwide	17–100 million
   H2N2	1957–1958 “Asian flu”, worldwide	1–4 million
   H3N2	Hong Kong flu, worldwide	1–4 million
   H1N1	1977 Russian flu, worldwide	700,000
   H1NI/09	2009 Swine flu, worldwide	151,700–575,400
   H1N1	2015 Indian Swine flu in India	2,035




3. Cholera 

   One of the most dangerous diseases, cholera, involves an acute intestinal infection caused by the bacterium Vibrio Cholerae. Contaminated food and water are the common mediums of spread and can lead to small outbreaks. These outbreaks can spread quickly if sanitation systems are not managed properly. 
    

   Common symptoms of cholera include vomiting, profuse cramping and watery diarrhoea. If the person is not treated on time, the symptoms can turn severe, causing death within hours. 
    

   Outbreak	Occurrence	Number of deaths
   First Cholera Pandemic	1817–1824 in Asia and Europe	100,000+
   Second Cholera Pandemic	1826–1837 in Asia, Europe and North America	100,000+
   Third Cholera Pandemic	1846–1860, worldwide	1 million+
   Fourth Cholera Pandemic	1863–1875 in the Middle East	600,000
   Fifth Cholera Pandemic	1881–1896 in Asia, Africa, Europe and South America	298,600
   Sixth Cholera Pandemic	1899–1923, in Europe, Asia and Africa	800,000+
   Eighth cholera Epidemic	1947 in Egypt	10,277
   Seventh Cholera Pandemic	1961–1975, worldwide	Unknown
   Bangladesh Cholera Epidemic	1991 in Bangladesh	8,410–9,432
   Latin America Cholera Epidemic	1991–1993 in Peru, Chile, Ecuador, Bolivia, Colombia, Mexico, El Salvador and Guatemala	8,000
   Zimbabwean Cholera Outbreak	2008–09 in Zimbabwe	4,293
   Haiti Cholera Outbreak	2010-2019 in Haiti	10,075
   Yemen Cholera Outbreak	2016–2021 in Yemen	3,886 (as of 30th November 2019)




4. Smallpox

   Now eradicated through vaccination, smallpox has been the most dangerous disease in the world. It is a contagious viral infection caused by the Variola virus. Humans are the only hosts of smallpox. Transmission may occur due to direct contact with the infected person, contaminated bedding or clothing or through bodily fluids. The origin of the smallpox virus is unknown, but it has been around for centuries. 
    

   In 1798, Edward Jenner paved the way for vaccination that helped tackle the disease. Fever, skin rashes, vomiting and fluid-filled bumps were common symptoms of smallpox. 
    

   Outbreak	Occurrence	Number of deaths
   Japanese Smallpox Epidemic	735-737	2 million
   Mexico Smallpox Epidemic	1520	5-8 million
   Chile Smallpox Epidemic	1561	Unknown
   Iceland Smallpox Epidemic	1707-1709	18000+
   North Carolina Smallpox Epidemic	1738-1739	7,700–11,700
   North American Smallpox Epidemic	1775-1782	11,000+
   New South Wales Smallpox Epidemic	1789-1790	Unknown
   New South Wales Smallpox Epidemic	1828-1829	19,000
   Great Plains Smallpox Epidemic	1837	17,000+
   Pacific Northwest Smallpox Epidemic	1862	20,000+
   Europe Smallpox Epidemic	1870-1875	500,000
   Smallpox Epidemic in India	1974	15,000




5. HIV/AIDS

   Human Immunodeficiency Virus (HIV) is a viral infection that affects the body’s immune system. The most advanced stage of HIV is known as Acquired Immunodeficiency Syndrome (AIDS). HIV has been around since 1981, killing millions. 
    

   Unprotected sexual contact, infected blood transfusion and intravenous drug use are some causes of HIV transmission. HIV is the world’s deadliest virus that destroys the white blood cells of the human body. It gradually weakens the immunity of the infected person. As a result, the person becomes more prone to infections and diseases like tuberculosis and cancer. 
    

   At the end of 2022, around 39 million people were living with HIV across the globe. While there is no cure for the disease, antiretroviral treatment and awareness have helped reduce HIV-related deaths globally. 
    

6. Ebola

   Ebola is caused by the Ebola filovirus. It is a rare and deadly disease and was first discovered in 1976. While several Ebola outbreaks have erupted in Africa, the outbreaks between 2013 and 2016 have been the most devastating. 
    

   Around 28,600 people got infected, and 11,325 people died in Guinea, Sierra Leone and Liberia. Bats are considered natural hosts of the Ebola virus. The disease can spread through infected bodily fluids, contaminated objects like syringes and direct contact with vomits. Fever, severe headache, sore throat, diarrhoea, bleeding, and bruising and decreased liver and kidney function are some symptoms of Ebola. 
    

7. Dengue

   Dengue is spread by the Aedes species of mosquito carrying the dengue virus. The earliest report of this disease is from 1779. Since then, till the 20th century, dengue cases were few. However, ecological disruption has led to more frequent dengue outbreaks. 
    

   Dengue is a tropical disease and causes symptoms like headache, high fever, muscle and joint pain and skin rash. Acute cases can involve severe fever, hemorrhagic bleeding and even death. Luckily, a vaccine for the dengue virus is now available. 
    

8. Malaria

   Malaria is caused by the female Anopheles mosquito carrying malaria parasites. The symptoms of the disease include tiredness, fever, headaches and vomiting. Severe cases of malaria can also involve seizures, yellow skin, coma and even death. If not treated properly, malaria symptoms can reoccur after months or years. 
    

   Outbreak	Occurrence	Number of deaths
   South America Malaria Epidemic	1600-1650	Unknown
   Pacific Northwest Malaria Epidemic	1829-1833	1,50,000
   Netherlands Malaria Epidemic	1829	2,800
   Ceylon Malaria Outbreak	1906	80,000
   Egypt Malaria Epidemic	1942-1944	Unknown
   India Malaria Outbreak	2006	17




9. COVID-19

   The COVID-19 disease was first reported in 2019 in Wuhan. It soon turned into a pandemic and spread across the globe like wildfire. COVID-19 not only led to unprecedented lockdowns, but its social and economic impacts are still lingering. 
    

   The disease is caused by SARS-CoV-2, which is one of the world’s most deadliest viruses. The disease can be transmitted via droplets and airborne particulars expelled by infected people. Symptoms of COVID-19 usually appear after 2 to 14 days of virus exposure. 
    

   Mild symptoms can include fever, loss of smell and fatigue. While there is no standard cure for coronavirus disease, you can manage it through vaccines, antivirals and oxygen support. As of September 2023, around 6.9 million people have died of the COVID-19 disease.

Wrapping Up

For centuries, human lives have been ravaged by several diseases. Earlier, the impact of these diseases was limited to some regions. However, increased human population and global travel have the potential to turn local outbreaks into global threats, as seen in the recent COVID-19 pandemic. Hence, staying protected against communicable diseases is more crucial than ever. 
 

Buying a health insurance plan is one of the ways to tackle disease outbreaks. It ensures you remain free from financial worries while fighting against illnesses. You can also invest in a life insurance policy to give your loved ones a financial safety net.