Antonine Plague

The Antonine Plague of AD 165 to 180, also known as the Plague of Galen (after Galen, the Greek physician who described it), was a prolonged and destructive epidemic, which affected the Roman Empire. It was possibly contracted and spread by soldiers who were returning from campaign in the Near East. Scholars generally believed the plague was smallpox, due to the skin eruptions over the entirety of the body which appeared to be red and black (Horgan), although measles has also been suggested, and recent genetic evidence strongly suggests that the most severe form of smallpox arose in Europe much later. As yet, there is no genetic evidence from the Antonine plague.

Ancient sources agree that the plague is likely to have appeared during the Roman siege of the Mesopotamian city of Seleucia in the winter of 165–166, during the Parthian campaign of Lucius Verus. Ammianus Marcellinus reported that the plague spread to Gaul and to the legions along the Rhine. Eutropius stated that a large proportion of the empire's population died from this outbreak. According to the contemporary Roman historian Cassius Dio, the disease broke out again nine years later in 189 AD and caused up to 2,000 deaths a day in the city of Rome, 25% of those who were affected. The total death count has been estimated at 5–10 million, roughly 10% of the population of the empire. The disease was particularly deadly in the cities and within the Roman army.

The Antonine plague occurred during the last years of the Pax Romana, the high point in the influence, territorial control, and population of the Roman Empire. Historians differ in their opinions of the impact of the plague on the empire in the increasingly troubled eras after its appearance. Based on archaeological records, Roman commercial activity in the Indian Ocean extending to the Indian subcontinent and Southeast Asia from ports of Roman Egypt seems to have suffered a major setback after the plague. This disruption likely contributed to a broader economic decline and social instability throughout the empire in the years that followed.