Since the beginning of time disease and illnesses have plagued mankind. As we have evolved and spread across the globe, so have infectious viruses. While outbreaks have been fairly common in modern times, the majority did not reach the pandemic levels that COVID-19 has. Widespread disease developed when society shifted to agricultural communities. Trade between communities created new opportunities for interactions between humans and animals. As trade became standard, the scale and spread of these diseases began to increase dramatically.

Epidemics such as the plague, smallpox, tuberculosis, and others first appeared during these early years. As society advanced, larger cities were created, and living in close proximity to each other and animals, with poor sanitation and nutrition, were breeding grounds for disease. Exotic and overseas trade routes spread these novel infections far and wide, creating the first global pandemics. Since then, many more widespread diseases have evolved including Cholera, the Spanish flu, and now Coronavirus. Read more to learn about the deadliest pandemics in history.

The Plague of Justinian

The plague of Ashdod, by Nicolas Poussin, 1630.

In 541 CE, the Plague of Justinian arrived in Constantinople, the capital of the Byzantine Empire. The disease traveled across the Mediterranean Sea from Egypt, which had recently been conquered by Emperor Justinian. Egypt paid tribute to the Emperor in grain and plague-infested fleas road on the backs of black rats that ate the grain. The plague swept through Constantinople and spread like wildfire across the globe, killing between 30 and 50 million people, roughly half the world’s population.

Procopius of Caesarea was a prominent late antique Byzantine scholar who became the principal historian of the 6th century. He is commonly classified as the last major historian of the ancient Western world. In his book Secret History, Procopius described victims as suffering from delusions, nightmares, fevers, and swellings in the groin, armpits, and behind their ears. He recounted that some lapsed into comas while others became highly delusional. Victims either suffered for days before death or died almost instantaneously after the onset of symptoms.

Thomas Mockaitis, a history professor at DePaul University said, “People had no real understanding of how to fight it other than trying to avoid sick people. As to how the plague ended, the best guess is that the majority of people in a pandemic somehow survive, and those who survive have immunity.”

The Black Death

The Black Death hit Europe in 1347 and claimed the lives of 25 million people in four years. Signs of infection included extremely swollen lymph nodes that if left untreated, would spread to the blood or lungs, along with pus-filled boils that pop and bleed, chills, vomiting, diarrhea, and terrible aches and pains. After the onset of symptoms, death was imminent. But Mockaitis said that even though people had no concept of contagion, they understood that it was correlated to proximity.

Ingenious officials in the Venetian-controlled port city of Ragusa enforced a law known as Trentino. This law required sailors to isolate themselves on their ships for 30 days until they could prove they weren’t ill. As time went on, lawmakers increased forced isolation to 40 days or a Quarantino, the origin of the word quarantine, and hence the beginning of people going into quarantine to fight viruses. This law inspired the western world to follow suit and implement these practices.

The Great Plague of London

London never fully recovered from the Black Death. From 1348 to 1665, variations of the disease resurfaced every decade. There were 40 outbreaks over 300 years, and with each epidemic, 20 percent of the city’s population died. By the early 1500s, Britain imposed the first laws to separate and isolate the sick. Plague stricken households were marked by bales of hay strung to a pole outside. It was also mandatory for people who were exposed to infected family members to carry a white pole when out in public. It was believed that cats and dogs were carriers of the plague, so there was a massacre of hundreds of thousands of animals.

The Great Plague of 1665 was the final and one of the severest epidemics of the centuries-long outbreaks, which killed 100,000 Londoners in seven months. All forms of public entertainment were banned and victims were forcibly shut into their homes to prevent the spread of the disease. Shutting the sick in their homes and burying the dead in mass graves was the only solution to containing the virus.

Once people began quarantining, the plague began to decline considerably. And though London continued to report plague victims until 1679, the major outbreak essentially ended by September 2, 1666, when a baker named Thomas Farriner unintentionally started the Great Fire of London. Farriner accidentally set fire to his house and ended up sending over 13,000 other homes up in flames.

The Great Fire destroyed most of the official city, which was much smaller than modern-day London. However, it didn’t reach many of the surrounding areas such as Whitechapel, Clerkenwell, and Southwark that were also exposed to the plague. So although the fire did drive out the plague-ridden rats in the 436 acres it burned, it didn’t spread far enough to rid greater London of the rodents.

There is no way of knowing for sure that the fire had any part in extinguishing the disease. Plague deaths in London were already declining when the fire began and people continued to die from it after the fire ended. It’s also not clear exactly when people began saying that the fire ended the plague because at the time people didn’t believe that to be true.

Smallpox

Dr. Jenner performing his first vaccination, by Ernest Board, 1796.

Smallpox relentlessly ravaged Europe, Asia, and Arabia for centuries. Signs of the illness included high fever, fatigue, a headache, backaches, and flat red rashes. It killed three out of ten people it infected and left the rest with pockmarked scars.

But the death rate of the Old World was nothing compared to the annihilation of the native populations in the New World when the virus arrived in the 15th century with the first European explorers. The native peoples of modern-day Mexico and the United States had zero natural immunity to smallpox and the virus killed them by the tens of millions.

Mockaitis said, “There hasn’t been a kill off in human history to match what happened in the Americas—90 to 95 percent of the indigenous population wiped out over a century, Mexico went from 11 million people pre-conquest to one million.”

It would be centuries before a British doctor named Edward Jenner would discover that milkmaids infected with a milder virus called cowpox seemed immune to smallpox. In 1796, Jenner famously inoculated his gardener’s 9-year-old son with cowpox and then exposed him to the smallpox virus with no ill effect. Smallpox became the first virus ever to be ended by a vaccine. And though it took two hundred more years, the World Health Organization announced that the virus had been completely eradicated from the face of the earth in 1980.

Cholera

Depiction of the depraved conditions in Atholone, by P.S Gilmore, 1849.

Cholera wreaked havoc on England, killing tens of thousands of people. At the time, it was believed that the disease was spread by foul air known as a “miasma.” But a British doctor named John Snow conjectured that the mysterious disease, which killed its victims within days, lingered in London’s drinking water. Symptoms of the disease include, diarrhea, vomiting, thirst, leg cramps, and restlessness or irritability. In severe cases dehydration can lead to kidney failure, shock, coma, and death within hours.

Snow investigated hospital records and morgue reports to track the precise locations of deadly outbreaks, acting as a scientific Sherlock Holmes. Over the course of 10 days, he created a geographic chart of cholera deaths. His results indicated that there was a cluster of 500 fatal infections neighboring the Broad Street pump, a popular city well for drinking water.

With great determination and perseverance, Snow was able to convince local officials to render the drinking well useless. By removing the pump handle, the infections dried up like magic. Though Snow’s work didn’t completely cure cholera, it did eventually lead to global efforts in improving urban sanitation and protecting drinking water from contamination. While it's wonderful that cholera has virtually been eliminated from developed countries, it’s still a serious disease in third-world countries lacking adequate sewage treatment and access to clean drinking water.

Tuberculosis (TB)

A young husband sitting next to his wife who has just died from tuberculosis, Cristobal Rojas, 1886.

Descriptions of TB first appeared in medical literature in the 17th century. However, the contagious nature of the disease was suspected as early as 1546 when Girolamo Fracastoro, an Italian physician and scholar, wrote that bedsheets and clothing of a consumptive could possibly contain contagious particles. TB is most frequently associated with symptoms involving the lungs, as these organs are most commonly affected by the disease, but it can affect any organ in the body. Usual indications include fever, chills, night sweats, cough, loss of appetite, weight loss, blood in the sputum (phlegm), and loss of energy. These symptoms can vary on a spectrum from mild to critical. For some, they may not seem serious, and for others, the symptoms become chronic and severe.

In 1720, an English physician named Benjamin Marten was the first to suspect that TB could be caused by "minute living creatures'', better known as a bacterium called Mycobacterium tuberculosis. He suspected that coming into contact with a consumptive individual could contract the disease.

By the 19th century, TB was the leading cause of death, killing one in seven people around the world. Constructions of care facilities dedicated to targeting TB were established to combat the deadliest disease of the era. These sanatoriums were built to isolate patients from the community and create a more comfortable experience for them, as well as research the virus to learn how to cure it. In articles from The Atlantic in the 1860s, American doctors explained their method. It was their belief that lifestyle adjustments could allow TB patients to manage their illness and heal enough to enter back into society.

Today, the United States has one of the lowest TB case rates in the world, and the 2019 case count represented the lowest number of TB cases on record. Yet too many people still suffer from the disease; our progress is too slow in eliminating TB this century. To end the deadly virus, it will require a dual approach of maintaining and strengthening the current TB control priorities, while increasing efforts to limit infection rates in high-risk populations.

Spanish Flu

Emergency hospital in Camp Funston, Kansas, 1918, Otis Historical Archives, National Museum of Health and Medicine.

The Spanish Flu pandemic began in 1918, and was the deadliest virus in history. This variant of influenza infected roughly 500 million people around the globe, about one-third of the planet’s population. It killed an estimated 20 million through 50 million victims. 675,000 of them were American.

The flu was first recorded in Europe, the United States, and areas of Asia before sweeping the globe. At the time there was no effective solution to cure this deadly flu strain, but it was mandated that all citizens wear masks, and all forms of entertainment and businesses be shut down as bodies were piled up in makeshift morgues before the virus ended its deadly war against the globe.

The virus attacks the respiratory system, and is highly contagious. When someone infected coughs, sneezes or talks, respiratory droplets form and are transmitted into the air where it can then be inhaled by anyone nearby. Additionally, whoever touches something with the virus on it and then touches his or her mouth, eyes or nose can become infected.

By the summer of 1919, the flu pandemic ended and those infected with the virus either developed immunity or died. Nearly a century later, in 2008, scientists discovered what made the Spanish Flu so deadly; the flu was generated by three different genes which enabled the virus to weaken its victim’s bronchial tubes and lungs which allowed for bacterial pneumonia to travel through them.

Since 1918, there have been several influenza outbreaks, although none as deadly. A flu pandemic from 1957 to 1958 killed around 2 million people worldwide, including some 70,000 people in the United States. And a pandemic from 1968 to 1969 killed around 1 million people, including some 34,000 Americans.

Coronavirus (COVID-19)

Medical workers in protective suits attend to novel coronavirus patients at the intensive care unit (ICU) of a hospital in Wuhan, Hubei province, 2020, China Daily via REUTERS.

The Coronavirus pandemic originated in Wuhan, China, in December of 2019 when dozens of people began treatment for pneumonia from an unknown source. Many of the them had visited a live animal market in Wuhan, but there was no evidence of the virus spreading from person to person.

On January 3rd, 2020 the World Health Organization declared the sixth "public health emergency of international concern," in our history. And by March 17th, ordered the "shelter in place" mandate. Since then, millions of people around the globe have fallen ill from the virus and hundreds of thousands of others have perished.

Anothony Fauci, the country’s leading expert on infectious diseases is confident that we can get control of this virus. He believes that if the country can uniformly implement public health guidelines such as wearing masks, keeping physically distanced, avoiding crowded situations, doing things outdoors more than indoors and washing hands frequently will decrease the amount of cases.

In an interview with Scientific American Fauci said, “We know from experience that the states or cities or countries that have done this have always been able to blunt and mitigate the slope of a surging curve such as this one.”

It can be difficult to make direct comparisons between pandemics as each develops in unique circumstances and has multiple factors to consider. The nature of the disease itself, and the social and political contexts in which the pandemic develops make considering the implications of the spread difficult to fully chart out. But scientific and medical advancements and knowledge of previous pandemics are able to help identify novel diseases such as COVID-19 more easily and containing outbreaks to achieve quicker results.

The one major commonality between all these viruses is personal hygiene. Good personal hygiene is extremely important for both your health and social reasons. Keeping your hands and body clean is vital in stopping the growth and spread of illness and infection. This simple habit is not only beneficial for your own health, but it can help protect those around you.

We are currently facing the biggest health crisis in a century, and it has been an extremely challenging year for us all. But if our past has taught us anything it is that all pandemics are eventually extinguished, and sometimes even eradicated. We will get through this and one day we'll look back at this time as one of the most significant chapters in history.

The Worst Pandemics Throughout History