By Verity Murphy
In 430BC, during the Peloponnesian war against their great rival Sparta, the people of Athens were hit by a deadly disease that has defied diagnosis to this day.
By the end of the plague Athens had lost a third of its army
The Greek historian Thucydides survived a bout of this unknown killer and left a vivid account of its symptoms, which make for frightening reading.
"People in good health were all of a sudden attacked by violent heats in the head, and redness and inflammation in the eyes, the inward parts, such as the throat or tongue, becoming bloody and emitting an unnatural and fetid breath," Thucydides starts by saying.
But that was just the beginning - sneezing and coughing were next, then diarrhoea, vomiting and violent spasms.
Next came livid skin, covered in pustules and ulcers, and a burning, unquenchable thirst.
Scholars believe the Antonine Plague was most likely smallpox
Most died around the seventh or eighth day, but if not the disease moved to the bowels, where violent ulceration and worsening diarrhoea, combined with exhaustion, was usually enough to prove fatal.
A handful did survive, but the disease left its mark - toes, fingers, genitals and sight were often lost.
For others the legacy was an entire loss of memory, so that, as Thucydides says, they "did not know either themselves or their friends".
The world's first recorded pandemic had arrived.
Thucydides says the disease began in Ethiopia, spreading through Egypt and Libya, then into the Greek world.
Over the next four years it killed almost a third of the Athenian population and its armed forces, along with the city's leader and mastermind of Athenian glory, Pericles.
It is unsurprising perhaps that the word pandemic is derived from Greek - "pan" meaning all, and "demos" meaning people.
By the 2nd Century AD, the mantle of European power had passed to Rome, largely thanks to the might of its army.
10,000 people were said to be dying in Constantinople each day
But this army almost proved the civilisation's downfall, when in AD165, troops returning from campaigns in the east of the empire brought back a disease which killed an estimated five million people.
Known as the Antonine Plague, after Marcus Aurelius Antoninus, one of two Roman emperors who died from the disease, it killed a quarter of those who caught it.
In AD166, the Greek physician and writer Galen travelled from Rome to his home in present-day Turkey and recorded some of the disease's symptoms.
In his treatise Methodus Medendi, he describes fever, diarrhoea, and inflammation of the pharynx, along with dry or pustular eruptions of the skin after nine days, symptoms which has led scholars to conclude the disease was most likely smallpox.
A second outbreak occurred between AD251 and 266, and at its height some 5,000 people were said to be dying in Rome every day.
But even this extraordinary toll was surpassed when in the 6th Century AD, under the reign of the Byzantine Emperor Justinian I, a plague hit the city of Constantinople.
The disease is thought to have begun in Ethiopia or Egypt and spread northwards via ships transporting huge quantities of grain to the city's great public granaries.
The bubonic plague killed an estimated 137 million worldwide
A now familiar tale of disease-ridden fleas, carried on the backs of ship-borne rats, the Plague of Justinian, as it came to be known, was in fact the first great pandemic of the bubonic plague.
From AD541 to 542 it killed 40% of Constantinople's population, with the Byzantine historian Procopius claiming that at its peak the plague was killing 10,000 people in the city every day.
The disease fanned out across the eastern Mediterranean, wiping out a quarter of the region's population.
A second major outbreak in AD588 went further, spreading up into France, leaving an estimated final death toll for the disease of about 25 million.
For the next 800 years, Europe was spared the misery of another pandemic, but in the middle of the 14th Century, the Plague of Justinian disease returned - only this time it bore another name.
Now known as the Black Death, thanks to the blackening of the skin which victims suffered through haemorrhaging under the skin, the disease arrived from Asia.
People fled in its path, but instead of escaping as they had hoped, they merely aided its spread across the continent.
Cholera is still a killer in the developing world
From 1347 to 1350, the Black Death killed at least a quarter of Europe's population - an estimated 25 million people.
There were similar bubonic plague outbreaks in Asia and the Middle East at the same time, indicating that it was a global pandemic.
Bubonic plague outbreaks occurred repeatedly in Europe, reportedly gathering strength with each generation, until the 1700s.
By then the estimated worldwide death toll for the bubonic plague had reached a dizzying 137 million.
Cities under threat
Urban areas were particularly affected by the Black Death, with the disease often claiming 50% of the population in cities.
The next pandemic was also worse in cities, where poor sanitation provided a perfect breeding ground.
Cholera had been described by Portuguese physician Garcia de Orta in the 16th century, but it was in 1816 that the disease went truly global.
Spanish flu killed more people than World War I
Already endemic to India, the disease now spread along trade routes into Russia and Eastern Europe, before shifting to Western Europe and even North America.
The world has been ravaged by no less than seven cholera pandemics, six of them starting in the 19th Century, with every continent except Antarctica suffering outbreaks.
The most recent occurred in 1961, starting in Indonesia, and though modern sanitation has curbed the disease's power, it is still a killer today.
Young people hit
Cholera may have been the scourge of the 19th century, but in the 20th Century it was influenza.
During the last century there were three flu pandemics. The first and worst, the Spanish flu, started in 1918 in three far-flung locations: Brest, in France; Boston in the US; and Freetown in Sierra Leone.
The disease had an incredibly high mortality rate and unusually people aged 20-40 were its victims rather than the old and weak.
It also moved across the globe with breathtaking speed, killing 25 million people in the course of six months; a fifth of the world's population was infected.
The disease disappeared almost as fast as it had appeared, but by then it had killed an estimated 40 million people, more than had died in World War I, which was coming to an end at the time.
For many years the precise strain of flu could not be identified, but new research conducted by the US Armed Forces Institute of Pathology indicates that it most probably originated in birds.