In “How Plagues Really Work,” Wendy Orent’s new Aeon piece, she argues that the next pandemic won’t likely come from bird flu genes but from the crowded, inhospitable conditions of refugee camps or overwhelmed hospitals, where disease incubates. Considering how many war-torn areas there are in the world right now, that’s cause for concern. An excerpt which looks at an example from Ancient Greece:

“One mysterious ancient outbreak, the Great Plague of Athens, shows how deadly epidemics unroll in time. The Plague – said to have been caused by typhus, measles, small pox or Ebola, depending on whom you ask – exploded in Athens in the summer of 430 BCE, during the early days of the Peloponnesian War, a 27-year struggle between Athens and Sparta over hegemony in the Hellenic world. Pericles, the de facto leader of Athens, who pushed for war, developed a defensive strategy that proved fatal, to him and to as many as a third of Athenian citizens. He insisted on bringing all citizens – people who lived in the towns and rural areas outside the walled city – into Athens, leaving the rest of the city-state to be ravaged by the invading Spartans. The Athenian Long Walls ran down to the separate ports of Piraeus and Phaleron, each of which lay about four miles from the City of Athens proper. Thus sealed off, fronting only on the sea, Athenians could shelter safely, Pericles argued, until the Peloponnesian War was won.

The normal population of the city was around 150,000. Scholars estimate that 200,000 to 250,000 farmers and townsmen and their families came streaming in, bringing everything they could carry with them – down to the woodwork on their farmhouse walls. But Pericles had made no provision for the newcomers, who were used to their country manors, their quiet towns, their open fields. A few had homes or relatives within the walls. But most had nowhere to go, and huddled in stifling huts, or in tents flung up in the narrow spaces between the walls. The crowded encampments were ripe for virulent infection.

Physicians and attendants died quickly, and the only people who could care for the sick were survivors immune to further infection.”