The Antonine Plague, AD 165–180, also known as the Plague of Galen, who described it, was an ancient pandemic, either of smallpox or measles, brought back to the Roman Empire by troops returning from campaigns in the Near East. The epidemic may have claimed the life of Roman emperor Lucius Verus, who died in 169 and was the co-regent of Marcus Aurelius Antoninus, whose family name, Antoninus, was given to the epidemic. The disease broke out again nine years later, according to the Roman historian Dio Cassius, and caused up to 2,000 deaths a day in Rome, one quarter of those infected. Total deaths have been estimated at five million. The disease killed as much as one-third of the population in some areas and decimated the Roman army.
Ancient sources agree that the epidemic appeared first during the Roman siege of Seleucia in the winter of 165–66. Ammianus Marcellinus reports that the plague spread to Gaul and the legions along the Rhine. Eutropius asserts that a large population died throughout the Empire.
In 166, during the epidemic, the Greek physician and writer Galen traveled from Rome to his home in Asia Minor. He returned to Rome in 168 when summoned by the two Augusti; he was present at the outbreak among troops stationed at Aquileia in the winter of 168/69. Galen's observations and description of the epidemic in the treatise Methodus Medendi is brief, and his other references to it are scattered among his voluminous writings. He describes the plague as "great" and of long duration and mentions fever, diarrhea, and inflammation of the pharynx, as well as a skin eruption, sometimes dry and sometimes pustular, appearing on the ninth day of the illness. The information provided by Galen does not clearly define the nature of the disease, but scholars have generally preferred to diagnose it as smallpox.
Historian William McNeill asserts that the Antonine Plague and the later Plague of Cyprian (251–ca.270) were outbreaks of two different diseases, one of smallpox and one of measles, although not necessarily in that order. The severe devastation to the European population from the two plagues may indicate that people had no previous exposure to either disease, which brought immunity to survivors. Other historians believe that both outbreaks were of smallpox. This latter view seems more likely to be correct given that molecular estimates place the evolution of measles sometime after 500 AD.
In their consternation, many turned to the protection offered by magic. Lucian of Samosata's irony-laden account of the charlatan Alexander records that a verse of his "which he despatched to all the nations during the pestilence... was to be seen written over doorways everywhere"—particularly in those houses which were emptied, Lucian remarks.
The epidemic had drastic social and political effects throughout the Roman Empire: Barthold Georg Niebuhr concluded that "as the reign of M. Aurelius forms a turning point in so many things, and above all in literature and art, I have no doubt that this crisis was brought about by that plague... The ancient world never recovered from the blow inflicted on it by the plague which visited it in the reign of M. Aurelius." Edward Gibbon and Michael Rostovtzeff assign the Antonine plague less influence than political and economic trends, respectively.
Some direct effects of the contagion stand out, however. When Imperial forces moved east under the command of Emperor Verus after the forces of Vologases IV of Parthia attacked Armenia, the Romans' defense of the eastern territories was hampered when large numbers of troops succumbed to the disease. According to the 5th-century Spanish writer Paulus Orosius many towns and villages in the Italian peninsula and the European provinces lost all their inhabitants. As the disease swept north to the Rhine, it also infected Germanic and Gallic peoples outside the Empire's borders. For a number of years, these northern groups had pressed south in search of more lands to sustain their growing populations. With their ranks thinned by the epidemic, Roman armies were now unable to push the tribes back. From 167 until his death, Emperor Marcus Aurelius personally commanded legions near the Danube, trying with only partial success to control the advance of Germanic peoples across the river. A major offensive against the Marcomanni was postponed until 169 because of a shortage of Imperial troops.
During the Germanic campaign, Marcus Aurelius also wrote his philosophical work 'Meditations'. Passage IX.2 states that even the pestilence around him is less deadly than falsehood, evil behavior, and lack of true understanding. As he lay dying, Marcus uttered the words, "Weep not for me; think rather of the pestilence and the deaths of so many others."
- H. Haeser's conclusion, in Lehrbuch der Geschichte der Medicin und der epidemischen Krankenheiten III:24–33 (1882), followed by Zinsser 1996.
- "There is not enough evidence satisfactorily to identify the disease or diseases" concluded J. F. Gilliam in his summary (1961) of the written sources, with inconclusive Greek and Latin inscriptions, two groups of papyri and coinage.
- Dio Cassius, LXXII 14.3-4; his book that would cover the plague under Marcus Aurelius is missing; this later outburst was the greatest of which the historian had knowledge.
- "Past pandemics that ravaged Europe", BBC News, November 7, 2005
- Plague in the Ancient World
- Martin Sicker, (2000). "The Struggle over the Euphrates Frontier". The Pre-Islamic Middle East. (Greenwood) 2000:p.169 ISBN 0-275-96890-1.
- Eutropius XXXI, 6.24.
- See McLynn, Frank, Marcus Aurelius, Warrior, Philopshoper, Emperor, Vintage Books, London, 2009.
- D. Ch. Stathakopoulos Famine and Pestilence in the late Roman and early Byzantine Empire (2007) 95
- Furuse Y, Suzuki A, Oshitani H (2010) Origin of measles virus: divergence from rinderpest virus between the 11th and 12th centuries. Virol J. 7:52.
- Lucian, Alexander, 36.
- Niebuhr, Lectures on the history of Rome III, Lecture CXXXI (London 1849), quoted by Gilliam 1961:225
See also 
- Marcus Aurelius. Meditations IX.2. Translation and Introduction by Maxwell Staniforth, Penguin, New York, 1981.
- McNeill, William H. Plagues and Peoples. Bantam Doubleday Dell Publishing Group, Inc., New York, 1976. ISBN 0-385-12122-9.
- Gilliam, J. F. "The Plague under Marcus Aurelius". The American Journal of Philology 82.3 (July 1961), pp. 225–251.
- Zinsser, Hans. Rats, Lice and History: A Chronicle of Disease, Plagues, and Pestilence. Black Dog & Leventhal Publishers, Inc., 1996. ISBN 1-884822-47-9.
- Bruun, Christer, "The Antonine Plague and the 'Third-Century Crisis'," in Olivier Hekster, Gerda de Kleijn, Danie+lle Slootjes (ed.), Crises and the Roman Empire: Proceedings of the Seventh Workshop of the International Network Impact of Empire, Nijmegen, June 20–24, 2006. Leiden/Boston: Brill, 2007 (Impact of Empire, 7), 201-218.