Top 10 Deadly Pandemics by Death Toll in the World

Throughout history, human civilization has been periodically reshaped by forces beyond its control. Among the most profound of these are pandemics—widespread outbreaks of disease that sweep across continents, claiming lives on a staggering scale and leaving indelible marks on societies, economies, and cultures. These events are more than just historical footnotes; they are catalysts for change, testing the resilience of populations and the progress of medicine. This listicle explores ten of the most significant pandemics recorded, detailing their origins, paths, and devastating human costs. By looking back at these chapters of our shared past, we can appreciate the scale of challenges humanity has faced and overcome.

1. The Black Death (1346–1353)

The Black Death was a bubonic plague pandemic occurring in Afro-Eurasia from 1346 to 1353.The disease was caused by the bacterium Yersinia pestis. The origin of the Black Death is disputed, with the pandemic originating either in Central Asia or East Asia, but its first case was reported in Crimea in 1347. From Crimea, it was carried by fleas living on the black rats that traveled on Genoese slave ships. Once it came ashore, the Black Death spread through North Africa, Western Asia, and the rest of Europe and the Italian Peninsula through fleas and person-to-person contact. The number of deaths is estimated between 75–200 million people in Eurasia and North Africa, making it one of the deadliest pandemics in history and the most fatal pandemic recorded in human history. The Black Death was the second great natural disaster to strike Europe during the Late Middle Ages and is estimated to have killed 30 percent to 60 percent of the European population. The plague might have reduced the world population from c. 475 million to 350–375 million in the 14th century.

2. Spanish Flu (1918–1920)

The Spanish flu was an unusually deadly influenza pandemic caused by the H1N1 influenza A virus.Lasting from February 1918 to April 1920, it infected 500 million people—about a third of the world's population at the time—in four successive waves. The first observations of illness and mortality were documented in the United States (in Kansas) in March 1918 and then in April in France, Germany, and the United Kingdom. The death toll is typically estimated to have been somewhere between 20 million and 50 million, although estimates range from a conservative 17 million to a possible high of 100 million, making it one of the deadliest pandemics in human history. The 1918 Spanish flu was the first of three flu pandemics caused by H1N1 influenza A virus; the most recent one was the 2009 swine flu pandemic.

3. Plague of Justinian (541–549 AD)

The Plague of Justinian,or Justinianic Plague (541–549 AD), was the first major outbreak of the first plague pandemic and the first Old World pandemic of plague, the contagious disease caused by the bacterium Yersinia pestis. The disease afflicted the entire Mediterranean Basin, Europe, and the Near East, severely affecting the Sasanian Empire and the Byzantine Empire and especially its capital, Constantinople. The plague is named for the Byzantine emperor in Constantinople, Justinian I (r. 527–565) who, according to his court historian Procopius, contracted the disease and recovered in 542, at the height of the epidemic which killed about a fifth of the population in the imperial capital. The contagion arrived in Roman Egypt in 541, spread around the Mediterranean Sea until 544, and persisted in Northern Europe and the Arabian Peninsula until 549. The estimated death toll for this pandemic is between 15 and 100 million people, affecting 25–60% of the European population.

4. HIV/AIDS Pandemic (1981–Present)

The HIV/AIDS pandemic is an ongoing global health crisis.A reconstruction of its genetic history shows that the HIV pandemic almost certainly originated in Kinshasa, the capital of the Democratic Republic of the Congo, around 1920. HIV made the jump from other primates to humans in west-central Africa in the early-to-mid 20th century. AIDS was first recognized by the United States Centers for Disease Control and Prevention (CDC) in 1981 and its cause—HIV infection—was identified in the early part of the decade. In 1983 the HIV virus was discovered and identified as the cause of AIDS. By 2009, AIDS had caused nearly 30 million deaths. An estimated 37 million people worldwide were living with HIV in 2018, with 680,000 deaths having occurred in that year. An estimated 20.6 million of these live in eastern and southern Africa. Between the time that AIDS was identified (in the early 1980s) and 2020, the disease has caused an estimated 36 million deaths worldwide. HIV/AIDS is considered a pandemic—a disease outbreak which is present over a large area and is actively spreading.

5. Third Plague Pandemic (1855–1960)

The third plague pandemic was a major bubonic plague pandemic that began in Yunnan,China, in 1855 during the fifth year of the Xianfeng Emperor of the Qing dynasty. This episode of bubonic plague spread to all inhabited continents. The disease is caused by a bacterium usually transmitted by the bite of fleas from an infected host, often a black rat. The network of global shipping ensured the widespread distribution of the disease over the next few decades. It ultimately led to more than 12 million (perhaps 15 million) deaths in India and China, with about 10 million killed in India alone, making it one of the deadliest pandemics in history.

6. Cocoliztli Epidemic of 1545–1548

The cocoliztli epidemic,or the great pestilence, is a term given to millions of deaths in the territory of New Spain in present-day Mexico in the 16th century attributed to one or more illnesses collectively called cocoliztli, a mysterious illness characterized by high fevers and bleeding. It ravaged the Mexican highlands in epidemic proportions from 1545 to 1548. The disease became known as Cocoliztli by the native Aztecs and had devastating effects on the area’s demography, particularly for the indigenous people. Estimates for the entire number of human lives lost during this epidemic have ranged from 5 to 15 million people, making it one of the most deadly disease outbreaks of all time. It killed an estimated 27–80% of the Mexican population.

7. Antonine Plague (165–180 AD, possibly up to 190)

The Antonine Plague of 165 to 180 AD,also known as the Plague of Galen (after Galen, the physician who described it), was an ancient pandemic brought to the Roman Empire by troops who were returning from campaigns in the Near East. Scholars have suspected it to have been either smallpox or measles. Ancient sources agree that the plague appeared first during the Roman siege of the Mesopotamian city Seleucia in the winter of 165–166. Ammianus Marcellinus reported that the plague spread to Gaul and to the legions along the Rhine. Eutropius stated that a large proportion of the empire's population died from this outbreak. According to the contemporary Roman historian Cassius Dio, the disease broke out again nine years later in 189 AD and caused up to 2,000 deaths a day in Rome, one quarter of those who were affected. The plague may have claimed the life of a Roman emperor, Lucius Verus, who died in 169 and was the co-regent of Marcus Aurelius. The total death count has been estimated at 5–10 million, and the disease killed as much as one third of the population in some areas and devastated the Roman army.

8. COVID-19 Pandemic (2019–Present)

The COVID-19 pandemic is an ongoing global pandemic of coronavirus disease 2019(COVID-19) that is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was identified in Wuhan, China, in December 2019; a lockdown in Wuhan and other cities in Hubei province failed to contain the outbreak, and it spread to other parts of mainland China and around the world. The World Health Organization (WHO) declared the outbreak a Public Health Emergency of International Concern on 30 January 2020, and a pandemic on 11 March 2020. As of July 25, 2021, more than 194 million cases have been confirmed, with more than 4.16 million confirmed deaths attributed to COVID-19, with estimates ranging from 4.2 to 8.9 million deaths, making it one of the deadliest pandemics in history. The estimated global infection fatality rate is 0.05%–0.1%.

9. 1520 Mexico Smallpox Epidemic (1519–1520)

The history of smallpox in Mexico spans approximately 500 years from the arrival of the Spanish to the official eradication in 1951.The 1520 Mexico smallpox epidemic was a pivotal event within this history. It was brought to Mexico by those in Spanish ships, then spread to the center of Mexico, where it became a significant factor in the fall of Tenochtitlan. The epidemic occurred from 1519 to 1520 and resulted in an estimated 5–8 million deaths, which represented 23–37% of the Mexican population at the time.

10. 1957–1958 Influenza Pandemic (Asian Flu)

The 1957–1958 Asian flu pandemic was a global pandemic of influenza A virus subtype H2N2 that originated in Guizhou in southern China.The first cases were reported in Guizhou of southern China, in 1956 or in early 1957. They were soon reported in the neighbouring province of Yunnan in late February or early March 1957. By the middle of March, the flu had spread all over China. The number of deaths caused by the 1957–1958 pandemic is estimated between one and four million worldwide, making it one of the deadliest pandemics in history, with an estimated fatality rate of 0.03–0.1%. A decade later, a reassorted viral strain H3N2 further caused the Hong Kong flu pandemic (1968–1969).