Whilst security concerns typically revolve around armies and nations, the greatest threat to humanity throughout our brief existence comes instead from the most insignificantly tiny lifeforms. Infections and diseases have throughout history laid low kings, destroyed empires, and felled the average person by the hundreds of millions. From the Black Death, culling half of Europe in just five years, to Spanish flu, claiming more lives than the global conflict it succeeded, our ancestors endured an enemy they could not see and understood little of. Today, even armed with modern medicine as we are, we still should not forget the threat posed by the smallest living things sharing our planet.
Here are 20 of history’s most devastating plagues and epidemics:
20. Plaguing our species since the dawn of time, the earliest humans were forced to endure deadly pandemics in a cruel natural sifting of genetic purity
Approximately 100,000 years ago, during the Paleolithic Era, the first known case of plague afflicted humanity. Although details are scarce, gleaned from the slightest traces in archaeological remains, during our early ancestors’ residence in Africa it is believed that a great plague descended upon the region. Decimating the homo sapien population, which dropped potentially as low as just 10,000, the epidemic almost rendered our species extinct. In so doing, however, it is believed the survivors were sufficiently strengthened on a genetic level to endure future outbreaks and pandemics to consequently procreate through the ages.
The oldest known specific strain of plague, dating to approximately 5,000 years ago, the end of the Neolithic Era, and centered on modern-day Sweden, similarly reflects our evolutionary history and longstanding interaction with deadly infections. Believed to have spread along emergent trade routes at the start of the Bronze Age, in conjunction with the birth of settlements encompassing 10,000-20,000 inhabitants, this sudden boom in population density created an ideal breeding ground for plague. Persisting ever since, humanity’s advancement and centralization accelerated the evolution of our ancient microbial enemy and laid the stage for thousands of years of deadly, if invisible, bacterial warfare.
19. The Plague of Athens struck the Greek city as it desperately fought for its independence in the Peloponnesian War against Sparta, killing approximately one-quarter of its population
The Plague of Athens, affecting the city-state of Athens during the second year of the Peloponnesian War, was an epidemic of devastating proportions and consequences. Crippling the Athenian war effort, and possibly altering the eventual outcome of the conflict, the disease, believed to have originated in Ethiopia and entering Greece through the port of Piraeus, was recorded by Thucydides as so severe that it dwarfed all previous plagues. Killing approximately one-quarter of the population of Athens in 430 BCE, and returning again in 429 and 427, the citizens of Athens lived under a virtual death sentence and descended into near-anarchy and terror.
In the centuries since the plague, more than thirty possible conditions have been suggested by epidemiologists as the infectious cause. Traditionally regarded as an early form of the bubonic plague, modern assessments have broadened to include a range of alternatives including smallpox, measles, or typhus. Other suggestions, drawing inspiration from Thucydides’ description, have suggested explanations closely connected to Africa’s unique medical history, including Ebola or a strain of hemorrhagic fever. Analyses are complicated by the recurrence of disease due to the conditions of the city, with a definitive answer likely lost to history.
18. Killing at its peak as many as 2,000 people per day in the city of Rome, the Antonine Plague devastated the Roman Empire during the 2nd century
The Antonine Plague, also known as the Plague of Galen, was an ancient pandemic that devastated the Roman Empire between 165 and 180 CE. Imported into Roman territory from the Near East by soldiers returning from military campaigns abroad, the initial outbreak of the plague is believed to have been responsible for the death of Roman Emperor Lucius Verus, co-ruler with Marcus Aurelias, in 169. After subsiding for a few years, in 178 the plague exploded once again; across this collective time period, it is estimated the epidemic was responsible for the deaths of approximately five million.
Killing at its peak 2,000 people per day in Rome, in addition to as much as one-third of the population in certain regions of the empire, the disease carried a mortality rate of roughly twenty-five percent. The prolonged nature of the plague resulted in crippling consequences to Roman military effectiveness, with major offensives in Germania postponed due to a lack of soldiers. The precise nature of the plague is uncertain, with Galen describing the condition as resulting in fevers, diarrhea, pharyngitis, as well as skin lesions and pustules. Modern scientific opinion has generally coalesced around a consensus that the Antonine Plague was a form of smallpox.
17. Contributing to the Crisis of the Third Century, the Roman Empire was almost felled by the Plague of Cyprian during the 3rd century
The Plague of Cyprian, named for the Bishop of Carthage who witnessed and described the effects of the outbreak, was a pandemic afflicting the Roman Empire between 249 and 262 CE. Contributing to the Crisis of the Third Century, the widespread outbreak resulted in severe shortages of food production and the capacity of the empire to project its military might. At the height of the plague, according to contemporary sources the outbreak was responsible for as many as five thousand deaths per day in Rome. Concurrently, the persecution of Christians in the Roman Empire spiked, with acolytes of the fledgling religion scapegoated for the tragedy.
Nearly bringing about the end of the Roman Empire, with a rapid succession of usurping emperors and unrepentant in-fighting, the frontier, insufficiently manned and weakened, collapsed. Only the efforts of subsequent emperors, including notably Diocletian and Constantine, saved the state from implosion and total erasure. Given the nature and spread of the pandemic, it is generally believed that the inhabitants of Rome enjoyed no immunity to the condition and thus had not been exposed previously. As a result, the most prominently subscribed to suggestions include influenza, Ebola, and measles.
16. Devastating the Eastern Roman Empire the Plague of Justinian stands among the most deadly of global pandemics, responsible for the deaths of tens of millions
Afflicting the Eastern Roman Empire, in particular its capital, Constantinople, as well as the port cities of the Mediterranean Sea, the Plague of Justinian was one of the deadliest pandemics in human history. Named for Emperor Justinian I, the Byzantine Emperor during an outbreak in 541 and 542 CE, the pandemic, viewed by some historians as worldwide in scope, bears significant parallels in impact to the Black Death centuries later. Over the course of a series of outbreaks spanning two centuries, the plague was responsible for the deaths of an estimated twenty-five to fifty million people, representing thirteen to twenty-six percent of the global population.
Killing as many as 5,000 people per day in Constantinople at the height of the outbreak, the imperial city lost as much as forty percent of its population. Never truly recovering its former glory, the social and cultural impact of the plague was devastating. After sustained investigation, in 2013 medical researchers finally isolated the bacterium responsible for the plague: Yersinia pestis. Believed to originate from the Tian Shan mountain ranges on the border of China, the Plague of Justinian reflects the potential negative consequences of the opening up of the Silk Road and the increased inter-connectivity of the world.
15. The Plague of 664, the first recorded plague in English history, coincided with a solar eclipse to convince the inhabitants of the British Isles that it was divine punishment
The Plague of 664, the first recorded plague in English history, was a localized epidemic contained within the British Isles that began in the year 664 of the Common Era. Split between two periods of primary outbreak, 664-668 and a second reemergence between 680 and 686, the unknown plague was responsible for widespread death and disruption throughout the British Isles. An exception to the plague was northern Scotland which, for unknown reasons but likely due to remoteness rather than genetic factors, remained seemingly unaffected by the outbreaks; contemporary sources attributed this fortune to intervention by St. Columba.
Coinciding with the rare occurrence of a total solar eclipse in May 664, as well as possibly an earthquake, the arrival of the deadly plague was interpreted by many as divine retribution upon the inhabitants of the British Isles. The Christian churches of Britain, in particular, took great advantage of the outbreak to advance the Christianization of pagan Britons, promoting the alleged immunity of the priesthood due to divine protection. This propaganda, combined with the eerie spectacle of a solar eclipse, resulted in a notable swing away from traditional religious beliefs in favor of Christianity in the British Isles.
14. The smallpox epidemic of 735-737 decimated the Japanese islands, reinforcing negative perceptions of the outside world and causing major political upheavals
Affecting much of Japan, the smallpox epidemic of 735-737 devastated the insular Asian nation. Inflicting adult mortality at rates as high as thirty-five percent upon the Japanese population, with some regions suffering even worse casualties, the disease, originating on the island of Kyushu, quickly spread to the capital at Nara. Affecting all classes of society equally, the rigid hierarchy of Japanese culture was laid bare, with all four brothers of the powerful Fujiwara clan killed in 737 by the outbreak. This event precipitated a major political reorganization of the state, with longstanding rival Tachibana no Moroe instead able to leverage himself into a position of power.
Believed to have been introduced to Japan by fishermen who had contracted it during time on the Korean peninsula, the pandemic was assisted by official dignitaries returning from the court of Korea in 736. Triggering significant shortages in labor, in particular concerning rice cultivation, the Japanese state was forced to take unprecedented action to rectify the damage. In the years after the epidemic, attempts were made to stimulate dangerously low agricultural productivity by offering land to commoners on the condition they work said land; this generous offer resulted in the births of many future households that would emerge into prominence centuries later.
13. Responsible for killing half of the population of Europe in just five years, the consequences of the Black Death took centuries to recover from
The Black Death, known historically as the Great Plague, stands among the deadliest instances in recorded human history. Originating in the plains of Central Asia, the plague was carried by fleas on rats along the Silk Road into the borderlands of Europe and Mediterranean ports. Enjoying a surprisingly brief peak, lasting from just 1347 until 1351, this outbreak is estimated to have caused the deaths of between seventy-five and two hundred million people across Eurasia and Europe. In total, killing between thirty and sixty percent of the population of Europe, the Black Death reduced the world’s population so much that it would take nearly two hundred years to recover.
Beyond the catastrophic loss of life, the deaths of half of Europe’s population in less than five years resulted in irreversible political, economic, and social upheavals. Religious persecutions, particular of Jews, who were accused of poisoning the water supplies, spiked, with 2,000 Jews murdered en masse in Strasbourg in February 1349. For those who survived the outbreak, however, they enjoyed vastly improved economic opportunities, with available land and cheap property abundant. The Black Death also replenished Mother Nature, with whole forests regrowing in the absence of human industry, even affecting global temperatures and climate.
12. Believed to be responsible for the deaths of approximately eighty percent of the Aztec people, “cocoliztli” killed tens of millions in the centuries following the Spanish arrival in the Americas
Spanning at least twelve outbreaks, including three major epidemics in the 16th century in the aftermath of Spanish arrival, “cocoliztli”, as the disease was termed by the native Aztecs, devastated the indigenous population of Mexico. First appearing in around 1520, the outbreak of 1545-1548, in particular, caused an immeasurable and fatal impact upon the Aztec civilization. Daily death tolls in the cities of Tlaxcala and Cholula ranged between 400-1,000 people, contributing to an estimated death toll of five to fifteen million people representing potentially as much as eighty to ninety percent of the indigenous population at this time.
Crucial to the reduction of the Aztec population from thirty million in 1519 to less than two million by 1700, the precise cause of the epidemic remains unknown. Major occurrences of “cocoliztli” typically appeared within two years of a major drought, lending credence to suggestions of a vermin-carried hemorrhagic fever. Symptoms, however, remain similar to many “Old World” diseases, including measles and typhus. Recent archaeological study has uncovered evidence of Salmonella enterica during the time of the outbreak, resulting in speculation that the epidemics might have been a unique concoction of immensely deadly afflictions.
11. In the years directly preceding the arrival of English settlers aboard the Mayflower, the indigenous population of New England was all but destroyed as a result of infectious outbreaks of a European disease
A classic example of a “virgin soil epidemic”, in which “the populations at risk have had no previous contact with the diseases that strike them and are therefore immunologically almost defenseless”, the years prior to English arrival in New England saw the indigenous population of New England suffer one of the deadliest disease outbreaks in history. Between 1616 and 1619, the Wampanoag, inhabitants of modern-day Massachusetts and Rhode Island, were decimated in what was later proclaimed by early English settlers as divine intervention to cleanse the land prior to white arrival on the continent.
Originally thought to have been smallpox, although now suggested to have been a form of leptospirosis, the illness was introduced to the indigenous tribes by contact with French traders to the north. Resulting in a mortality rate close to guaranteed, with no viable medical treatment available, it is estimated that population losses were in excess of ninety percent. One should not entirely absolve European colonists of responsibility, however, for viral outbreaks in the Americas. Some, notably the deliberate use of smallpox as a biological weapon against indigenous peoples during the Siege of Fort Pitt in 1763, were purposeful acts of unquestionable genocide.
10. Lasting only a couple of years, the Great Plague of Milan was responsible for the deaths of millions and the downfall of Venice as a leading power of Europe
One of the later major appearances of the disease, the Italian Plague of 1629-1631, also known as the Great Plague of Milan, was a series of outbreaks of bubonic plague that spread across northern and central Italy. Believed to have been initially transported to the city of Mantua in 1629 by German and French soldiers fighting in the Thirty Years’ War, the opposing Venetian forces contracted the disease and carried it with them into central Italy during their retreat. By 1630, the plague had reached Venice, Bologna, and Florence, and even reached as far south as Rome and Naples in the 1650s.
Decimating the populations of Italy, public health measures including quarantines proved only so effective. Between 1630 and 1631, Milan suffered an estimated 60,000 deaths out of a population of 130,000, Verona 33,000 from a total of just 54,000, whilst Florence lost twelve percent of its population. Venice, suffering losses of 46,000 from an approximate total of 140,000, demonstrates the knock-on effect of disease epidemics. The city, a major commercial and political center of Europe prior to the outbreak, proved unable to sustain its might and gradually drifted into obscurity as other powers surpassed it.
9. The Great Plague of London, which was followed by the Great Fire of London eighteen months later, culled around one-quarter of the poorer inhabitants of London in just eighteen months
The Great Plague of London, lasting from 1665 to 1666, was the last major outbreak of the bubonic plague in England. Lasting just eighteen months the plague is estimated to have been responsible for the deaths of approximately 100,000 people, amounting to almost one-quarter of the total population of London. Carried, as was typical of bubonic plague, by infected rat fleas, the outbreak was thwarted, inadvertently, by the onset of the Great Fire of London in September 1666. The resultant conflagration destroyed ninety percent of London houses, helping to cleanse the city of the pandemic ravaging it.
Unlike other previous pandemics, the Great Plague atypically affected mostly the poor. London, with a population of around 400,000, was more than twelve times larger than the next most populous city of England: Norwich. When the outbreak started, the wealthy retreated to their country estates whilst the poor, crammed into shanty towns with no sanitation, were left to rot. In the years prior to the Great Plague, outbreaks in the slums were not uncommon, with 30,000 deaths in 1603, 35,000 in 1625, and 10,000 in 1636. Worse still, with the exodus of the rich, as Samuel Pepys recorded, ” in Westminster, there is never a physician and but one apothecary left”.
8. The Great Plague of Vienna, part of a wider pandemic across Europe during the late-17th century, killed tens of thousands in the imperial city alone
The Great Plague of Vienna, striking the imperial city of the House of Habsburg in 1679 in a manner reminiscent of its London predecessor a decade earlier, was a crippling recurrence of the bubonic plague. Vienna, suffering persistently from periodic outbreaks ever since the first emergence of the bubonic plague in the fourteenth century due to its position as a trading hub, like many others so-afflicted was crippled by the epidemic. Claiming an estimated 76,000 inhabitants, doctors treated patients with the unscientific method of bloodletting before depositing the deceased in open-air pits exposing the wider population to greater infection.
Although memorialized as “of Vienna”, the city’s outbreak was merely one of a far larger epidemic across the neighboring regions. Caught at an intersection of the disease, infected from the West after earlier outbreaks there and from the East by trade routes from the source, several urban centers of Europe endured similar torments. Prague buried approximately 83,000 residents, the city of Halle in Germany lost almost half its population, whilst Dresden, Cologne, and Magdeburg, among other settlements, experienced their own plague outbreaks. It was not until 1707 that the epidemic subsided and disappeared from Germany at large.
7. Accompanying the Great Northern War, a plague outbreak obliterated the populations of several Eastern European cities and reduced national populations dramatically
The Great Northern War (1700-1721), fought between a Russian led confederacy against the Swedish Empire, was accompanied, as many conflicts were, with an outbreak of plague. Peaking between 1708-1712, the pandemic is believed to have entered Europe via Constantinople before spreading to eventually afflict a region spanning Central Asia to the Mediterranean. Provoking a hysterical response among contemporaries, unable to comprehend the cause and nature of transmission, quarantine protocols were instituted. Entire cities, including for example Königsberg, were isolated and plague houses became tantamount to death sentences.
Although the last major plague outbreak to affect the Circum-Baltic region, it registered among perhaps the worst since the Black Death itself. Whilst some regions and cities endured comparatively unscathed, with Hamburg, for instance, suffering nine to ten thousand fatalities equating to only ten to fifteen percent of the population, others, especially settlements in Prussia, were less fortunate. Malmö suffered losses of thirty to forty percent, Stockholm in excess of one-third, whilst Tallinn, Gdansk, and Riga suffered casualties exceed two-thirds of their population. In total it is estimated approximately 150,000 people were killed during just the peak years of the outbreak.
6. Introduced via French refugees fleeing a slave rebellion, the city of Philadelphia was rendered anarchic by an epidemic of Yellow Fever in 1793
In the spring of 1793, two thousand French refugees from the colony of Cap Français, Saint-Domingue, arrived in Philadelphia fleeing an on-going slave revolution on the island of Hispaniola. Unintentionally carrying individuals already infected with yellow fever, as well as a host of mosquitoes, by the autumn their arrival had triggered the first yellow fever outbreak for more than thirty years. Instigating a mass exodus from the temporary capital city of fifty thousand residents, the United States government, including President Washington, abandoned the city, and within six weeks more than twenty thousand people had fled into the surrounding countryside.
Peaking in October, almost 5,000 deaths were registered with yellow fever as the cause of death across a fourteen week period. Eventually, with winter incoming, the November frosts eradicated the imported mosquitoes and naturally ended the surging epidemic. The crisis exposed serious social cracks in American society, however, with neighboring settlements, panicked by the outbreak, denying aid or assistance to Philadelphians en masse resulting in a humanitarian disaster. Furthermore, blacks were enlisted in the inaccurate belief they were naturally immune to remove the bodies of the infected, resulting in racially disparate rates of contraction.
5. The first pandemic outbreak of cholera, the early 19th century saw the deadly infection plague cities throughout Asia on a scale never before seen
The First Cholera Pandemic, also known as the First Asiatic Cholera Pandemic, was an outbreak of the eponymous infection between 1817 and 1824. Beginning in the Indian city of Calcutta, which had long endured the effects of the deadly infection, for the first time a cholera epidemic spread throughout Asia and beyond to reach an unprecedented range of victims. Reaching Siam by March 1820, in May of the same year Bangkok and Manila became affected. The spring of 1821 saw Java, Oman, and China struck, whilst in 1822 Japan, the Persian Gulf, and the Caucuses were afflicted, and the choleric pandemic even reached Mauritius in 1823.
Affecting the soldiers of the British Empire, these personnel were intimately involved in the widespread transmission of the infection. Transporting the epidemic overland and by sea, the inter-connectivity of the imperial possessions played a huge role in elevating cholera to pandemic status. Whilst, due to the lack of official records, formal death tolls are difficult to calculate, it has been estimated that the outbreak was responsible for the deaths of hundreds of thousands. Bangkok suffered at least 30,000 fatalities, whilst in Semarang, on the island of Java, at least 1,225 died across just eleven days in April 1821 from cholera.
4. An inevitable product of mass migrations of desperate humans, the Great Famine, and the Irish exodus precipitated a typhus epidemic in North America in 1847
Caused by the mass Irish exodus as a result of the Great Famine, during which more than a million Irish emigrated, the typhus epidemic of 1847 afflicted the northern half of the East Coast of North America. Packing migrants aboard over-crowded and disease-ridden ships, known colloquially as “coffin ships”, these transports became ideal breeding grounds for the resultant epidemic. Many of these cities were unprepared for the influx of people, infected or otherwise, and struggled under the sudden burden. Quarantine areas were instituted once it became apparent many migrants were infectious, resulting in “fever sheds” being constructed.
The city of Montreal, a popular destination for Irish immigrants, saw between 3,500 and 6,000 of said migrants die as a result of typhus. Many, however, died arguably unnecessarily, packed into twenty-two tiny quarantine sheds, lacking appropriate medical care, and surrounded by armed guards to prevent their escape. In total, more than 20,000 inhabitants of Canada died between 1847 and 1848 from typhus. Equally, the fledgling United States was similarly affected. The arrival of Irish immigrants in New York City triggered an outbreak of typhus, with a mortality rate of at least eleven percent over a period of seven weeks.
3. Originating in the Russian city of Saint Petersburg, the flu pandemic of 1889-1890 rapidly spread throughout the globe to kill more than a million people within two months
Sometimes referred to as “Russian flu” or “Asiatic flu”, although not to be confused with the Russian flu strain known as H1N1, the pandemic of 1889-1990 was a worldwide outbreak of influenza. Assisted by the advancement of modern transport infrastructure, with the largest nineteen nations of Europe possessing a collective two hundred thousand kilometers of railway by the late-19th century, influenza, for the first time, was provided the opportunity to become truly global in scope. First recorded in Saint Petersburg in December 1889, within four months the virus had spread throughout the Northern Hemisphere.
Demonstrating the rapidity of its spread, the peak of the pandemic in the United States was the second week of January 1890. Taking just five weeks to reach peak mortality, more than one million people worldwide were killed by the outbreak. Originally thought to have been a strain of the H2N2 influenza virus, known as Asian flu and mutated from birds, modern medical analysis has cast doubt on this claim. Instead, it is widely suggested today that the pandemic was a result of the broader H3N8 strain, more commonly found in ducks, dogs, and horses.
2. “Spanish flu”, as the 1918 influenza pandemic became to be known, killed almost five percent of the world in the aftermath of the First World War
The 1918 influenza pandemic, colloquially known as “Spanish flu”, remains among the deadliest natural disasters in human history. Due to wartime censorship in Allied nations, neutral Spain, not being involved placed no such restrictions on the press, and the accurate reporting of outbreaks in the Iberian nation led people to incorrectly associate the illness with Spain. An atypically deadly flu pandemic involving the H1N1 strain of the virus, modern transportation, the close quarters of soldiers during World War I, the weakened condition of many of these soldiers, and the fast movement of troops, helped spread the virus as far away as the Pacific Islands and the Arctic.
A precise explanation for the high mortality rate is uncertain, with flu traditionally claiming the young or old; in contrast, Spanish flu predominantly killed healthy young adults. Infecting an estimated five hundred million people worldwide, approximately one-third of humanity, within the first year of the pandemic life expectancy in the United States dropped twelve years. Carrying a mortality rate of between ten and twenty percent, it is estimated the pandemic was responsible for the deaths of between fifty and one hundred million people, representing three to five percent of the global population, including as many as twenty-five million in the first six months.
1. The last pandemic to claim more than one million lives, “Hong Kong flu” spread quickly around the world but fortunately carried an atypically low mortality rate
The 1968 flu pandemic, more commonly referred to as “Hong Kong flu” and lasting between 1968 and 1969, was the product of mutations in the influenza virus. The first known outbreak of the H3N2 strain, descended from the H2N2 strain the new variant was a response to the traditionally avian virus mutating within a swine host. First appearing in the city of Hong Kong on July 13, 1968, Chinese authorities, failing to learn from an outbreak of Asian flu in 1957, were extremely slow to respond or issue warnings. By the end of July, outbreaks were reported in both Vietnam and Singapore, with India, the Philippines, Australia, and Europe infected by September.
Reaching the United States via troops returning from the Vietnam War in December, Africa and South America were eventually infected in 1969. Fortunately for humanity, compared to other flu pandemics Hong Kong flu carried a low mortality rate. This was chiefly because of a winter outbreak, some natural immunity after the Asian flu outbreak, and vastly improved medical care. Killing an estimated one million people worldwide, including 33,800 in the United States, a vaccine was developed as rapidly as possible and began being administered as early as 1968 to some patients.