While an epidemic is a sudden increase in the number of cases of a disease, a pandemic is when an epidemic spreads over several countries or continents.
A pandemic is the highest possible level of a disease. Cholera, bubonic plague, malaria, leprosy, smallpox, and influenza have been some of the most deadly killers in the world.
Here are 10 of the worst pandemics in history.
1. The Plague at Athens (430-427 BC)
The earliest recorded pandemic took place in the second year of the Peloponnesian War. Originating in sub-Saharan Africa, it erupted in Athens and would persist across Greece and the eastern Mediterranean.
The plague was thought to be typhoid fever. Symptoms included fever, thirst, bloody throat and tongue, red skins and legions.
According to Thucydides,
the catastrophe was so overwhelming that men, not knowing what would happen next to them, became indifferent to every rule of religion or law.
Historians believe as much as two-thirds of the Athenian population died as a result. The disease had a devastating effect on Athens and was a significant factor in its eventual defeat by Sparta and its allies.
By most accounts, the plague at Athens was the most deadly episode of illness in the period of Classical Greek history.
The most famous figure to fall victim to this plague was Pericles, the greatest statesman of Classical Athens.
2. Antonine Plague (165-180)
The Antonine Plague, sometimes referred to as the Plague of Galen, claimed almost 2,000 deaths per day in Rome. The total death toll was estimated to be around 5 million.
Thought to have been smallpox or measles, it erupted at the height of Roman power throughout the Mediterranean world, and affected Asia Minor, Egypt, Greece and Italy.
It was thought that the disease was brought back to Rome by soldiers returning from the Mesopotamian city of Seleucia.
Before long, the Antonine Plague – named for the Roman emperor Marcus Aurelius Antoninus, who ruled during the outbreak – had spread to the troops.
The Greek physician Galen described the symptoms of the outbreak as: fever, diarrhoea, vomiting, thirstiness, skin eruptions, swollen throat, and coughing which produced a foul odour.
Emperor Lucious Verus, who ruled alongside Antonius, was reported to have been among the victims.
A second and even more serious outbreak of the plague took place in 251-266, which claimed an upwards of 5,000 deaths a day.
In all, historians believe that a quarter to a third of the entire population of the Roman Empire died from the Antonine Plague.
3. Plague of Justinian (541-542)
The Plague of Justinian affected the Byzantine Eastern Roman Empire, especially its capital Constantinople as well as the Sasanian Empire and port cities around the Mediterranean Sea.
The plague – named after the emperor Justinian I – is regarded as the first recorded incident of the bubonic plague.
It was also one of the worst outbreaks of plague in human history, killing an estimated 25 million people – almost 13-26 percent of the world’s population.
The means of transmission was the black rat, which travelled on Egyptian grain ships and carts across the empire. Necrosis of the limbs was just one of the terrifying symptoms.
At its height, the plague killed around 5,000 people per day and resulted in the deaths of 40 percent of the population of Constantinople.
The outbreak continued to sweep throughout the Mediterranean world for another 225 years until finally disappearing in 750. Throughout the empire, nearly 25 percent of the population died.
4. Leprosy (11th century)
Although it had existed for centuries, leprosy grew into a pandemic in Europe in the Middle Ages.
Also known as Hansen’s disease, leprosy is due to a chronic infection of the bacterium Mycobacterium leprae.
Leprosy causes skin lesions that can permanently damage the skin, nerves, eyes and limbs.
In its extreme form the disease can cause loss of fingers and toes, gangrene, blindness, collapse of the nose, ulcerations and weakening of the skeletal frame.
Some believed it to be a punishment from God for sin, while others saw the suffering of lepers as similar to the suffering of Christ.
Leprosy continues to afflict tens of thousands of people a year, and can be fatal if not treated.
5. The Black Death (1347-1351)
The Black Death, also known as the Pestilence or the Great Plague, was a devastating bubonic plague that struck Europe and Asia in the 14th century.
It is estimated to have killed between 30 to 60 percent of Europe’s population, and an estimated 75 to 200 million people in Eurasia.
The epidemic was thought to have originated in the dry plains of Central Asia or East Asia, where it travelled along the Silk Road to reach Crimea.
From there, it was likely carried by fleas living on black rats that travelled on merchant ships across the Mediterranean and Europe.
In October 1347, 12 ships docked at the Sicilian port of Messina, their passengers mainly dead or covered in black boils that oozed blood and pus.
Other symptoms included fever, chills, vomiting, diarrhoea, aches, pain – and death. After 6 to 10 days of infection and sickness, 80% of infected people died.
The plague changed the course of European history. Believing that it was a kind of divine punishment, some targeted various groups such as Jews, friars, foreigners, beggars, and pilgrims.
Lepers and individuals with skin diseases such as acne or psoriasis were killed. In 1349, 2,000 Jews were murdered and by 1351, 60 major and 150 smaller Jewish communities had been massacred.
6. The Cocoliztli epidemic (1545-1548)
The cocoliztli epidemic refers to the millions of deaths that took place in the 16th century in the territory of New Spain, in present-day Mexico.
Cocoliztli, meaning “pest”, in Nahhuatl, was actually a series of mysterious diseases that decimated the native Mesoamerican population after the Spanish conquest.
It had a devastating effect on the area’s demography, particular for the indigenous people who had no developed resistances to the bacteria.
The symptoms were similar to Ebola – vertigo, fever, head and abdominal pains, bleeding from the nose, eyes and mouth – but also a dark tongue, jaundice and neck nodules.
It has been estimated that Cocoliztli killed as many as 15 million people at the time, or around 45 percent of the entire native population.
Based on the death toll, it is often referred to as the worst disease epidemic in the history of Mexico.
7. Great Plague of London (1665-1666)
The Great Plague was the last major epidemic of the bubonic plague to occur in England. It was also the worst outbreak of plague since the Black Death.
The earliest cases occurred in a parish called St Giles-in-the-Fields. The death count began to rise rapidly during the hot summer months and peaked in September, when 7,165 Londoners died in one week.
In the space of 18 months, an estimated 100,000 people were killed – almost a quarter of London’s population at the time. Hundreds of thousands of cats and dogs were also slaughtered.
The worst of the London plague tapered off in late 1666, around the same time as the Great Fire of London.
8. The Great Flu Epidemic (1918)
The 1918 influenza pandemic, also known as Spanish flu, has been recorded as the most devastating epidemic in history.
It infected 500 million people around the world, including people on remote Pacific Islands and in the Arctic.
The death toll was anywhere from 50 million to 100 million. Approximately 25 million of those deaths came in the first 25 weeks of the outbreak.
What was particularly striking about this pandemic was its victims. Most influenza outbreaks only killed juveniles, the elderly or people who were already weakened.
This pandemic however affected completely healthy and strong young adults, while leaving children and those with weaker immune systems still alive.
The 1918 influenza pandemic was the first involving H1N1 influenza virus. Despite its colloquial name, it did not originate from Spain.
9. The Asian Flu Pandemic (1957)
The Asian Flu Pandemic was an outbreak of avian influenza that originated in China in 1956 and spread worldwide. It was the second major influenza pandemic of the 20th century.
The outbreak was caused by a virus known as influenza A subtype H2N2, believed to have originated from strains of avian influenza from wild ducks and a pre-existing human strain.
In the space of two years, Asian Flu travelled from the Chinese province of Guizhou to Singapore, Hong Kong and the United States.
The estimated death rate was one to two million. In England, 14,000 people died in 6 months.
10. HIV/AIDS pandemic (1980s-present)
The human immunodeficiency virus, or HIV, is a virus that attacks the immune system, and is transmitted through bodily fluids, historically most often through unprotected sex, birth, and the sharing of needles.
Over time, HIV can destroy so many CD4 cells that the individual will develop the most severe form of an HIV infection: acquired immunodeficiency syndrome (AIDS).
Although the first known case of HIV was identified in the Democratic Republic of the Congo in 1959, the disease reached epidemic proportions in the early 1980s.
Since then, an estimated 70 million people have been infected with HIV and 35 million people have died from AIDS.
In 2005 alone, an estimated 2.8 million people died from AIDS, 4.1 million were newly infected with HIV, and 38.6 million were living with HIV.