- Are We Entering a New Age of Pandemics?0.14 MB
The first age of pandemics followed in the wake of farming, cities and trade, because infections leverage proximity and numbers to survive and evolve. After millennia of mass mortality, followed by two centuries of progress against plagues driven by sanitary and medical revolutions, will we allow a second age of pandemic death to flourish in the dense and connected world that progress has created? A poxed century can be avoided if we cooperate to respond.
The shift from prehistory to history was a shift to density. Even the most inefficient, early agriculture was associated with populations per square mile that were ten or twenty times higher than among nomadic groups. Farming brought humans into close living not only with each other, but with domesticated pigs, birds and cows that harboured species-hopping infections. This density—alongside links between populations—was vital to the emergence of mankind’s most deadly microbial adversaries. Measles, for example, mutated from a disease of cattle. It needs about five hundred thousand people living in close contact to survive, otherwise it dies out for lack of fresh victims to attack. New infections repeatedly assailed an ancient world of connected cities across large parts of Eurasia. The plague of Athens was one of the earliest reliably recorded of those pandemics. The city state was a major trading power, importing three million bushels of wheat a year from the Black Sea alone. According to the chronicler Thucydides, plague spread through North Africa and then invaded Athens in 430 BCE via the port city of Piraeus. Symptoms included “redness and inflammation in the eyes, the inward parts, such as the throat or tongue, becoming bloody and emitting an unnatural and fetid breath.”
This plague was not as deadly or widespread as one that came soon after Rome’s ambassadors first reached the Han emperor in China in 160 CE. Trading networks across the Eurasian Steppe helped spread a disease that might have been smallpox, which killed more than one in four people in parts of the empire. Later, in the sixth century, another pandemic from the Steppe finished off the Roman Empire altogether: an outbreak of Yersinia pestis, the plague of the Black Death. Rats carrying infected fleas boarded the grain ships of Alexandria, which travelled the Mediterranean, spreading the bacillus as they went.
Report by the Centre for Global Development