Since ancient times, humans have had to endure terrifying diseases and widespread plagues that managed to devastate entire populations and in some cases, even changed the course of history. Whereas plagues were often confined to certain geographical regions in ancient times, with the advent of more modern forms of transportation and an increasingly global trade and market in the past few centuries, diseases have spread around the world at a staggering pace. This has led to some terrifying pandemics.
Of course, as medical science has grown more sophisticated, the threats that illnesses pose to most individuals have been diminished. In fact, many epidemics of the late 19th and early 20th centuries prompted scientists to accomplish medical breakthroughs such as the smallpox and the polio vaccines, effectively enabling the world to keep once-horrifying diseases under better control. Thanks to a more sophisticated understanding of how diseases are transmitted and the availability of better medical care, nowadays epidemics are less of a threat than they have ever been before. Yet, certain parts of the world's population are still at risk of contracting many terrible sicknesses, and as some new diseases, such as MERS have recently shown, many serious illnesses can still pose a threat to the world's population.
The following are a few of the world's worst epidemics in recorded history, from ancient times until today.
- 10,000 BC – 1970s
Smallpox is a disease that has been with humans for thousands of years; in fact, evidence of it was discovered on the mummified body of an Egyptan pharoh. The disease killed a significant portion of the European population in the 18th century, including five reigning monarchs. It is also the disease that is primarily blamed for killing up to 90-95% of the people native to the Americas after Europeans and Africans first made contact with the “New World.” It is generally agreed that this epidemic, which the native people of the Americas had no resistance or prior knowledge of, helped pave the way for Europe to colonize the Americas. It has been suggested, for instance, that Spanish Conquistador Hernán Cortés, who caused the fall of the Aztec empire, more easily defeated the Aztecs because the disease had wiped out their once-significant population. As recently as the 20th century, smallpox caused an estimated 300-500 million deaths worldwide including 20,000 deaths in India in the 1970s. Because of vaccination campaigns in the 19th and 20th centuries, the disease was finally eradicated worldwide in 1979. It is the only infectious disease in human history to have been completely eradicated by vaccinations.
- Ancient times – today
The word for typhus comes from a Greek word meaning “hazy,” which is descriptive of the mental state of those who are affected by the disease. Epidemics spread throughout Europe in 16th-19th centuries and were especially common during war times, since the disease thrived in places where people were crowded together in unsanitary conditions like prisons and army barracks. More French soldiers died of typhus than were killed by Russians during Napoleon’s retreat from Moscow in 1812. During World War I, it caused and estimated 3 million deaths in Russia, and in World War II, typhus killed many of those who were held in concentration camps. Presently, there is an effective vaccine and now typhus epidemics only occur sporadically in Asia, Eastern Europe, the Middle East and parts of Africa.
8 The Plague of Athens
- 430-427 BC
This plague hit the ancient Greek city-state of Athens in 430 BC, which also happened to be the second year of the Peloponnesian War. Highly contagious, it spread to the eastern Mediterranean. It returned twice, in 429 BC and then in 427 BC. It is uncertain which specific disease caused this plague, though it has been hypothesized that it was possibly typhoid, typhus, smallpox or even anthrax. The author Thucydides wrote about it in his History of the Peloponnesian War and claimed it originated in Ethiopia. It was a catastrophic epidemic for Greece, which was at war with Sparta at the time: according to Thucydides, 1/3 of the city perished from the disease. It also led to a shift in social and religious attitudes by people who felt abandoned by their gods.
7 Plague of Justinian
- Byzantine Empire and the Mediterranean
- 541-542 AD
This pandemic affected the Byzantine Empire, the Sassanid Empire and many Mediterranean port cities and has been called one of the greatest plagues in history. Historians now believe that it was a form of the bubonic plague. During its height of severity in 541, up to 10,000 people were killed per day in Constantinople (although modern scholars place this number at around 5,000). Since there was no room to bury the dead, bodies were often left out in the open. The plague continued to return up to year 750. In the end, it killed 40% of the population of Constantinople and killed ¼ of the population of the eastern Mediterranean, which had significant social and political consequences at the time – such as the weakening of the Byzantine Empire - that affected the course of European history.
6 The Black Death
- Asia and Europe
The Black Death, a general term for several forms of plague including the Bubonic plague and a form of blood poisoning, is thought to have originated in Southwestern/Central Asia. It spread to Europe in the 1300s through a trade route from China and was carried into several European ports by rats on merchant ships. It quickly spread throughout the Mediterranean and Europe and killed an estimated 75 million worldwide, including 20 million in Europe: this amounted to between 1/3 and 2/3 of the entire European population. The mortality rate of these diseases were high: 4 out of 5 people who contracted bubonic plague died, and more than 9/10 of those who contracted blood poisoning, or the pneumonic plague, died. The plague had a significant impact on European history: it prompted many religious, social and economic upheavals. It is also referenced in many famous works of literature and paintings.
5 Yellow Fever
- The Americas
Yellow Fever is spread by the bite of a female mosquito. Originally endemic in Africa, it was transferred to North and South America in colonial times. The first outbreak in the New World was in 1647 in Barbados and then another occurred in Mexico, followed by Brazil. Although it is a primarily tropical disease, it broke out in northern states several times, including New York in 1668 and Philadelphia in 1793. New Orleans suffered several major epidemics in the mid-1800s, which spread to Memphis in 1878; in the 19th century, it caused an estimated 20,000 deaths in the Mississippi Valley alone. The disease still exists today, and it is often recommended or even required that travellers to affected areas receive a vaccination.
- 1817-today, including 8 pandemics
Cholera is an old disease that had lingered in the Delta region in India for centuries. However, in 1817 it was finally transported out of that region to the rest of the world, making it the first global pandemic. At the time, a significant amount of the Indian population was affected and 10,000 British troops died. Thanks to the rise of fast, steam-powered passenger trains and ships, cholera then travelled on from India to almost every other part of the world, spread by sick travellers who contaminated local water sources. Since then, 7 cholera pandemics have developed throughout the world, mainly spread by contaminated water, although shellfish and plankton can also transmit the disease. Fortunately, cholera has been controlled by modern sanitary practices: the last major outbreak in the U.S. was in 1910-1911. It can also be treated with antibiotics and controlled by vaccines.
3 Spanish Flu
- 1918- 1920
In less than 2 years, this particularly nasty flu spread like wildfire – mainly facilitated by the movement of troops involved with World War I - across the globe and killed 50-100 million people worldwide (or around 3-5% of the global population). Like any flu, symptoms included sore throat, headaches and fever. However, it often progressed to something worse, including severe respiratory complications. Unlike most flu strains that affect the young, old or those with weakened immune systems, this flu mainly affected young adults with strong immune systems. It killed up to 20% of those infected. Because of wartime censors at the time, reports of the flu in Europe and the U.S. were minimized. Therefore, populations were not aware of how severe this flu was across the world until the pandemic was largely over after the war.
- United States/Europe
- 20th century
Although polio had existed for thousands of years in certain parts of the world, there were several epidemics in the 20th century including one in 1916 and another in 1952, making polio a significant and scary childhood disease throughout the century. U.S. president Franklin D. Roosevelt famously was a polio survivor after contracting it as an adult. Although 90% of polio infections cause no symptoms, if the virus enters the blood stream it can destroy motor neurons, which leads to muscle weakness and paralysis. The outbreaks prompted a race to find a vaccine for the disease. Thanks to improved medical practices, by the middle of the century the disease could be better controlled, and finally, in the 1950s, Dr. Jonas Salk developed a vaccine. Recently, however, outbreaks of polio have been reported in Asia, Africa and the Middle East.
1 Acquired Immune Deficiency Syndrome (AIDS)
- 1960s-present day
The human immunodeficiency virus, which causes the progressive failure of the immune system in humans, has led to the death of 25 million people worldwide since it was first clinically observed in 1981. An estimated 40.3 million people presently live with HIV. Its origins are uncertain, but it is believed to have originated in West-Central Africa. Although many people are still not aware that they are living with the virus, now there is more accurate testing and awareness of the disease and its transmission.