The Peloponnesian war has baffled historians for long. Among the epic conflicts of the ancient world, the war pitted the Greek city states of Athens and Sparta against each other. The seagoing Athenians met their match in the Spartans and their allies during a conflict that stretched from 431 bc to 404 bc. Led by the doughty Pericles, the Athenians held sway for much of the war, till a mysterious disease changed the balance of power. Based on the chronicles of Thucydides, historians have attributed Athens' defeat to a range of pathogens: Ebola fever, typhoid, anthrax, plague, smallpox, tuberculosis and measles.

Thucydides, a participant of the Peloponnesian war himself, also contracted the mysterious disease, but lived to describe the downfall of his country people. Healthy people were seized by "violent heat' in the head, their throats and tongues became bloody-red, and they emitted a "fetid' smell. Sneezing bouts, hoarseness of voice and painful coughing followed the initial symptoms. Stomach upsets and dry retching came next. Though there was no appreciable rise in body temperatures, "reddish and livid pustules and ulcers' appeared all over the sick. According to some estimates, the disease consumed more than 10,000 people