20 of History's Most Devastating Plagues and Epidemics

“Plague in an Ancient City”, depicting the Plague of Athens, by Michiel Sweerts (c. 1652-1654). Wikimedia Commons.

19. The Plague of Athens struck the Greek city as it desperately fought for its independence in the Peloponnesian War against Sparta, killing approximately one-quarter of its population

The Plague of Athens, affecting the city-state of Athens during the second year of the Peloponnesian War, was an epidemic of devastating proportions and consequences. Crippling the Athenian war effort, and possibly altering the eventual outcome of the conflict, the disease, believed to have originated in Ethiopia and entering Greece through the port of Piraeus, was recorded by Thucydides as so severe that it dwarfed all previous plagues. Killing approximately one-quarter of the population of Athens in 430 BCE, and returning again in 429 and 427, the citizens of Athens lived under a virtual death sentence and descended into near-anarchy and terror.

In the centuries since the plague, more than thirty possible conditions have been suggested by epidemiologists as the infectious cause. Traditionally regarded as an early form of the bubonic plague, modern assessments have broadened to include a range of alternatives including smallpox, measles, or typhus. Other suggestions, drawing inspiration from Thucydides’ description, have suggested explanations closely connected to Africa’s unique medical history, including Ebola or a strain of hemorrhagic fever. Analyses are complicated by the recurrence of disease due to the conditions of the city, with a definitive answer likely lost to history.