14 Deadly Diseases That Killed The Most In Human History

Last Updated On: July 9, 2018

Throughout history, diseases have been the chief slaughterer of humans. Fortunately, the 20th century witnessed developments in medicine that helped prevent enormous numbers of deaths. While some diseases’ killing has been on the wane including complete eradication of a few, other deadly diseases have been on the rise.

Usually, when people talk regarding the deadly diseases, the ones with high mortality rates and immediate killings spring to the minds of commons. The world’s true leading killers may, therefore, come as a surprise.

Here, I have compiled a list (ordered from the lowest to the highest death tolls) of 14 deadly diseases that killed the most and correspondingly marred the human history.


1. Lung Cancer is the deadliest form of cancer with over 1.38 million reported deaths globally in 2008 and a leading cause of deaths until 2014.

Cancer formation in the lungs.
Image credits: Cancer Research UK/Wikimedia, MahiroMomo/Pixabay

The mortality rates associated with lung cancer shot up during the 1930s due to the increasing popularity of cigarette smoking. Moreover, lung cancer had been among the leading causes of deaths globally until 2014, especially in the USA and Europe.

By no means does this imply that lung cancer is no more deadly. The American Cancer Society estimates 234,000 new cases of lung cancers with around 154,000 casualties in the US in 2018.

Smoking contributes to over 90% cases for men and around 80% for women. Some other contributing factors include exposure to radon (for miners) and carcinogens. Furthermore, this lethal form of cancer is far more common in ages of over 65.(1,2)

2. The Black Death (caused by bubonic plague) of the middle 14th century in Eurasia is among the worst pandemics in known history with a death toll of approximately 25-100 million.

A depiction of the Black Death in Florence in 1948.
Image source: Wellcome Trust via Wikimedia

The lethal pandemic, widely considered to be an outbreak of the bubonic plague originated in Europe in the mid-1300s. At an unprecedented scale, the outbreak wiped out over one-third of the European population within five years.

However, this pandemic was not the first known outbreak of the bubonic plague. In the 6th century, the disease rocked the Eastern Roman empire claiming a similar number of lives. In fact, there was another epidemic of the bubonic plague in the 19th century when around 80,000 more people lost their lives.(1,2)

3. Annually, cholera affects 1.3 to 4 million people worldwide and causes 21,000 to 143,000 casualties.

(left) A cholera patient receiving oral rehydration post cholera treatment.
Image credits: Centers for Disease Control and Prevention via Wikimedia, Wellcome Trust via Wikimedia

Cholera is an acute diarrheal disease commonly spread through polluted water. The WHO-released figures speak volumes about the severity of the disease.

The last major outbreak of cholera was in the USA in 1911. However, the disease still disrupts life in Africa and Southeast Asia. In industrialized countries, modern sewage treatment and clean water supply have virtually eradicated cholera.

Furthermore, cholera is an easily preventable and treatable disease. On 4 October 2017, the Global Task Force On Cholera Control (GTFCC) initiated the global strategy Ending Cholera: A Global Roadmap to 2030 to reduce cholera cases by 90% by 2030.(source)

4.The HIV (human immunodeficiency virus) is a fatal disease that catalyzes a condition known as AIDS (acquired immunodeficiency syndrome). Over 35 million globally have died of HIV.

HIV awareness in Africa.
Image credits: Mikael Häggström via Wikimedia, USAID U.S. Agency for International Development via Flickr

The HIV causes AIDS in humans, leading to progressive failure of the immune systems, thus making the body environment congenial to life-threatening cancers and infections.

Upon contraction, the average survival rate of HIV is 9-11 years. Also, the disease primarily spreads through sexual contact. The HIV is a subgroup of the retrovirus.

The Global Health Observatory (GHO) data from WHO cites that over 70 million people have contracted the HIV virus[2016 stats] ever since the beginning of the pandemic. At least 35 million of the population has succumbed to the deadly disease. Moreover, the most acutely affected region is the sub-Saharan Africa with nearly every 1 in 25 adults surviving with HIV.(1,2)

5. Diarrhea is a chief cause of deaths to infants below the age of five. Globally, there are over 1.7 billion new cases every year, and the disease kills approximately 525,000 of children on average.

Children under the age of five are vulnerable to diarrhea.
Image credits: SuSanA Secretariat/Flickr CC BY 2.0

The diarrhea is one of those diseases children can avoid to a significant effect with better sanitation, cleaner drinking water, and using soap during a hand wash. But the roots of the disease lie in the rotavirus for which vaccinations are globally available. Moreover, diarrhea continues to take the lives of children, primarily in the low and middle-income countries.

Fortunately, the death toll has fallen by approximately 51% from 1990 (2.58 million) to 2013 (1.26 million), and the numbers are decreasing every year. The casualties used to be as high as four million in the 1960s.(1,2)

6. The Spanish flu of 1918 is the deadliest pandemic of all time considering the immediate deaths. Estimates claim that 25 million people died within the first 25 weeks of the outbreak.

The 1918 Spanish flu in Oakland. California.
Image credits: Photo by Edward A. “Doc” Rogers. From the Joseph R. Knowland collection at the Oakland History Room, Oakland Public Library/Calisphere

The 1918 pandemic of the Spanish flu infected a population of over 500 million globally, approximately one-third of the total population then.

Flu, formally recognized as influenza, is a highly transmissible virus that attacks the respiratory system. Activities like coughing, sneezing, and even talking transmit the deadly virus. Some estimates claim that the death toll due to the Spanish flu was 50 to 100 million, making the pandemic one of the worst natural disasters in history.

Surprisingly, the genesis of the flu pandemic is mysterious even today. The flu apparently commenced in Europe, America, and parts of Asia before spreading all over the earth in a few months. However, the disease earned its name “the Spanish flu” since Spain was among the hardest hit countries. Even Spain’s King Alfonso XIII caught the fatal virus (did not succumb).(source)

7. Chronic Obstructive Pulmonary Disease (COPD) is among the leading causes of death in the USA today. As per the latest WHO stats, 3.17 million people died due to COPD in 2015 and there were over 251 million cases of the disease in 2016.

COPD is the third deadliest disease in USA today behind heart diseases and cancer.
Image credits: Air Force

There are two chief forms of COPD – chronic bronchitis and emphysema. Bronchitis is an inflammation of the airways to the lungs. The major symptom is coughing followed by mucus build-up. Emphysema is a lung disease that causes shortness of breath. Furthermore, women are about 37% more likely to have COPD than men.

Usually, people with the disease have a combination of the two, the reason primarily being tobacco smoking. Lung cancer and COPD are related, but not the same. Although the latter is not curable, treatments can reduce chances of death and relieve the symptoms.

Approximately 40 to 70% of lung cancer patients also have COPD. As per WHO stats 90% of the deaths prevail in lower and middle-income countries. Annually, the cost of countering chronic obstructive pulmonary disease is an estimated $50 billion in the USA alone.(1,2)

8. WHO reports that stroke is the second major cause of deaths globally. Around 15 million people contract strokes annually out of which at least five million die and another five million become permanently disabled.

Strokes cause 5 million deaths annually as per WHO.
Image credits: VSRao/Pixabay

A stroke occurs when the blood supply to the region in the brain responsible for memory and muscle control is cut off. Consequently, the oxygen deprivation kills the brain cells.

The strokes are of three types:

  • Ischemic strokes occur when there is an obstruction in the blood vessel that supplies blood to the brain. It accounts for nearly 87% of the strokes worldwide.
  • Hemorrhagic strokes – these strokes occur as a result of rupture of weakened blood vessels. The chief cause of this stroke is uncontrolled hypertension.
  • The minor strokes or transient ischemic attacks happen when a blood clot occurs temporarily. One must treat these warning strokes seriously.

Furthermore, the disease is a leading cause of disabilities in adults in the USA.(source)

9. Maternal and perinatal complications lead to approximately 5.6 million deaths of newborn babies and women. The complications chiefly consist of hemorrhage, high blood pressure, infection, and unsafe abortion.

Maternal and perinatal complications account for a staggering number of deaths of babies and women worldwide.
Image credits: Phillips, Kathy, Photographer/Wikipedia

WHO believes that the actual magnitude of the maternal and perinatal deaths remains under-reported. Approximately 303,000 women die during pregnancy and the day of childbirth. Furthermore, about 2.6 million babies turn out stillborn while another 2.7 million babies die within the next 28 days.[2016 stats]

The reason for under-reporting is not maintaining records of the majority of the stillborn babies and newborn deaths. In fact, countries often do not know the real statistics of the deaths and hence, the negligible precautions that could otherwise prevent a significant portion of these deaths.(source)

10. Ischemic heart disease, or coronary heart disease (CAD), is the #1 cause of deaths in most western countries. In fact, the disease led to 8.76 million deaths in 2015 making up for 15.9% of the worldwide deaths.

Coronary heart disease is the #1 disease causing deaths wordlwide.
Image credits: NIH: National Heart, Lung and Blood Institute

CAD is a heart disease marked by decreased blood flow to the heart. The coronary arteries are the only vessels that supply blood to the heart, and consequently, the latter’s blockage (a condition called atherosclerosis) induces the disease. In general, CAD represents a group of diseases such as myocardial infarction, angina, and sudden cardiac death.

The principal factors for CAD are high blood pressure, smoking, diabetes, sedentary lifestyle, high cholesterol levels, obesity, depression, and alcoholism. The symptoms of the disease include chest pain, heartburn, emotional stress, shortness of breath. However, people usually miss out on these symptoms, and a heart attack is the first noticeable symptom to detect CAD.

When combined, coronary heart disease and strokes contribute to over 13 million deaths every recent year.[2015 stats] (source)

11. The measles is among the deadliest diseases in human history. Between 1855 and 2005, an estimated 200 million people succumbed to the disease.

Measles killed 200 million humans between 1855 and 2005.
Image credits: CDC Global/Flickr

Measles is a highly transmissible viral disease. The disease, being airborne spreads through sneezing and coughing. Fortunately, the health measures taken across the globe have significantly reduced the worldwide deaths. The vaccination (introduced in 1960) caused an 84% decrease in deaths from 2000 (550,100) to 2016 (89,780). However, the reduction in deaths is a result of reduced mortality rates as approximately 20 million people still contract measles worldwide.[2014 stat]

However, the disease was far more deadly before the introduction of the vaccine. The genesis of the disease dates back to 500 AD. An outbreak of the disease in 1529 killed half of the population in Cuba and Honduras and later went on to wreck other countries such as Mexico and Central America. Furthermore, the disease killed 20% of the Hawaiian population in the 1850s, some 40,000 Fijians in 1875, and half of the Andamanese population in the 19th century. Until the introduction of the vaccination, approximately 7 to 8 million minors have died each year.(1,2)

12. Malaria, a mosquito-borne infectious disease, is among the deadly diseases as it slaughtered 100 million people between 1900 and 1950. The exact all-time death toll is mysterious but expected to be several hundreds of millions.

Malaria is in top 3 of the deadliest diseases that have killed the most in human history.
Image credits: Petaholmes/Wikimedia

The mosquito-borne transmittable disease is the chief killer of children. As per UNICEF estimates, malaria kills 3,000 children daily, and most of the deaths occur in children under the age of five. Furthermore, a staggering 90% of global malaria cases come from the epicenter sub-Saharan Africa.

The chief symptoms of malaria include fever, vomiting, headaches, exhaustion, dry cough, etc.

The disease is prevalent in lower and middle-income countries. Interestingly the rates of malaria had dropped from 2000 to 2014 by 37%, but they increased again. In fact, there were a reported 198 million malaria cases in 2014 and 214 million new cases in 2015. Until 2009, malaria killed at least one million children annually.(source)

13. Smallpox is a devastating, contagious disease that caused the death of 300 to 500 million people when it was prevalent.

Smallpox killed approximately 500 million people in human history, and in the top 2 of the deadly diseases that killed the most.
Image credits: Centers for Disease Control and Prevention via Wikipedia

The last reported case of smallpox was in 1977, and the WHO acknowledged the complete eradication of the deadly disease in 1980.

The genesis of the disease is the variola virus. Approximately 30% of the people contracting the disease have died while the rest remained scarred for life.

Historians believe that smallpox’s earliest cases were as early as 10,000 BC. The disease has marred the human history by sporadically ushering in the form of outbreaks. At least 400,000 Europeans died every year in the 18th century. In the USA, the Pontiac’s war of 1763 claimed the lives of an estimated 1.5 million Native Americans. The population of northern Japan decreased drastically due to smallpox. Furthermore, the Franco-Prussian war of 1870 spawned a smallpox pandemic that led to 500,000 casualties.

During the 1950s, there were as plenty as 50 million new cases of smallpox annually. The statistics mentioned above justify smallpox’s second position in the list of deadly diseases that killed the most.(1,2)

14. Tuberculosis (TB) leads the list of deadly diseases that have killed the most. Over 1 billion humans have succumbed to the disease, making TB the biggest executioner in history.

deadly diseases: Tuberculosis symptoms (left) and its prevalence around the world (right).
Image credits: By Mikael Häggström, used with permission via Wikimedia, Eubulides – WHO via Wikimedia

Despite being an antique disease, tuberculosis remains one of the top 10 causes of deaths even today. In fact, TB kills 40% of the HIV-positive patients.

The source of the contagious disease lies in Mycobacterium tuberculosis. Fossil remains have validated the prevalence of tuberculosis in prehistoric humans dating back to 4,000 BC. In fact, researchers have discovered Egyptian mummies from 3,200 BC with tubercular decays in the spines. Furthermore, TB was a leading killer in the 19th and 20th centuries, accounting for one-fourth of deaths in England in 1815 and one-sixth of casualties in France in 1918.

As per WHO, 25% of the world population has contracted the TB bacteria but is not ill. Approximately 10.4 million people fell ill with the disease in 2016, 1.7 million of these died. The most-affected countries today are in Asia and Africa – India, Indonesia, Philippines, China, South Africa, and Nigeria together account for 64% of the total TB cases.[2016 stats](1,2,3)

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