A terrible epidemic swept through the Roman Empire in the second half of the 2nd century, between 165 and 180 AD, claiming nearly five million lives—ten percent of the population. That fifteen-year period represented the most serious public health problem in the history of Ancient Rome—with the exception of the Justinian plague—and some historians believe it played an important role in triggering what we now know as the Crisis of the Third Century, as the demographic collapse limited the army’s ability to act and affected the economy by reducing the labor force in the fields, though others are not so certain. This is what we refer to as the Antonine Plague.

It is also called the Plague of Galen, as he, the personal physician of Emperor Marcus Aurelius and his co-emperor Lucius Verus, studied the symptoms and effects, describing them in his work Methodus medendi (“Method of Healing”). Galen, who was Greek by birth—originally from Pergamum, where he trained in the temple of Asclepius with two disciples of Hippocrates—settled in Rome in the year 162, achieving such a reputation that he was hired first by Consul Flavius Boethius and then by both emperors.

In 166, he made a two-year visit to his hometown, after which he returned to Rome and had the opportunity to witness a major outbreak of the Antonine Plague that occurred in Aquileia in the winter of 168. He documented his observations of the fever it caused, as well as other effects: thirst, diarrhea, violent coughing, skin eruptions with occasional pustules, pharyngitis, exhaustion… The limitations of the era prevented him from detailing much more, but his account is one of the documentary bases that some scientists use to suggest that it was smallpox.

Statue of Galen in his native Pergamon (present-day Bergama in Türkiye).
Statue of Galen in his native Pergamon (present-day Bergama in Türkiye). Credit: Bernard Gagnon / Wikimedia Commons

Galen was not the only one to refer to the epidemic, far from it, for when he came into contact with it in Aquileia, it had already been active for some time. Specifically, since the winter of 165, introduced by the army of General Gaius Avidius Cassius returning from Mesopotamia after the siege of Seleucia on the Tigris, a city that is now in Iraq and was then part of the Parthian Empire by the cession of Hadrian in 118. Some sources indicate that the first infection occurred after, in the midst of looting the Temple of Apollo in Babylon, a legionary broke a chest from which escaped what Dio Cassius calls a pestilential vapor.

This providential interpretation is corroborated by Ammianus Marcellinus, so an epidemic among the troops could have been the cause of the Roman retreat, although it must be taken into account that Avidius Cassius lacked the resources to hold the city after its conquest and that many of the losses suffered during the return were also due to supply problems. In any case, mass movements are often a good context for viruses and bacteria to spread, and during their return route, the legionaries spread the disease.

Thus, it was from Mesopotamia that it jumped to Egypt, where some papyri, such as the so-called Thmouis, narrate the devastating effects it had on the countryside and demographics, while the archaeological ruins of the town of Soknopaiou Nesos, in the Fayum Oasis, reveal that it was hastily abandoned in the 3rd century AD, likely due to being ravaged by the epidemic. In 166, it reached Asia Minor, and the disease that devastated Ephesus is identified with it, according to the account left by the sophist philosopher Aelius Aristides, who was infected in Smyrna but survived.

Another place where the epidemic struck was Antioch, on the current southern coast of Turkey, bordering Syria. Lucian of Samosata tells that there, an oracle written by the charlatan miracle-worker Alexander of Abonutichus, creator of the new cult of Glycon, a serpentine incarnation of Apollo, was found. One of his oracular verses was hung on the doors of houses as a protective amulet against contagion. Its effectiveness would be nil, but it managed to catch the attention of Marcus Aurelius, who consulted him about the fate of the campaign he was about to launch on the Danube against the Marcomanni.

Statue of Glycon from the 2nd century AD
Statue of Glycon from the 2nd century AD. Credit: ChristianChirita / Wikimedia Commons

Likewise, the oracles of the sanctuary of Claros, located near the Ionian city of Colophon, left records of epidemics that it is not clear if they refer to the Antonine Plague, given that the dates are uncertain; it is likely that some references are to it, while others are earlier or later, but they reflect the anxiety that the disease caused among people. It was no wonder, considering that it had already reached Europe; Ammianus Marcellinus recounts that it spread among the legions of Gaul and the Rhine. Considering that the Roman Empire encompassed nearly all the known world, the Antonine Plague became a true pandemic.

In fact, the situation was so serious that Lucius Verus and Marcus Aurelius (adopted sons of Antoninus Pius and both appointed co-emperors by Hadrian’s will), who were in the Danube to contain the Alemanni and Marcomanni, returned to Rome. The former, who had personally led the campaign against the Parthians, fell ill and died a few days later. It was then believed to be due to poisoning, but it is more likely that it was a stroke or even the Antonine Plague, which, as we mentioned, was already wreaking havoc by killing an average of two thousand people per day; ultimately, one-fourth of those infected. That was the context in which Galen worked.

Since both emperors belonged to the dynasty known as the Antonines, they ended up giving their name to the disease. It has an ironic point, since that period is considered the “golden age” of the Roman Empire, in the midst of the Pax Romana, with an economic prosperity that allowed it to reach about seventy-five million inhabitants, of which one million lived in Rome. That said, conditions were far from ideal, often overcrowded in insulae (popular housing blocks for the lower classes, who were the majority), high infant mortality, low life expectancy, and poor urban sanitation.

Ruins of the Temple of Apollo at Claros (Türkiye)
Ruins of the Temple of Apollo at Claros (Türkiye). Credit: Carole Raddato / followinghadrian.com / Wikimedia Commons / Flickr

The fact of being the metropolis par excellence meant that Rome received a multitude of foreigners daily, favoring the transfer of infectious diseases. The Romans were so accustomed to this that, paradoxically, they did not give it special importance in their time, and it was later authors who did so. In the year 169, the legions stationed on the Danube were decimated, forcing the Marcomannic campaign to be postponed for two years, suspending the discharge of veterans, and recruiting personnel from gladiators, bandits, and slaves, which allowed them to defeat the enemy.

By 171 there were no more invaders threatening the borders, but there was an equally or more dangerous adversary: the virus, which ironically must also have affected the Germanic people. But by 172 it had reached every corner of the empire, and although it had less impact on the western provinces due to being further away (and even so, it is known that the Spanish mines of Las Médulas had to close temporarily due to a lack of labor), it generally had a negative impact on the economy: price collapse, closure of construction companies because customers could not pay them, massive deaths of slaves in the countryside, where tenants were forced to accept longer contracts, decline in trade in the Indian Ocean…

In 180, Marcus Aurelius died in Pannonia, although it is not known for sure if the cause of his death was the Antonine Plague. It is unclear because this must be inferred from an inscription found in the Temple of Mithras in Virunum (in Austria), which some archaeologists consider a modern forgery, although others accept it as genuine. This lack of certainty is a constant derived from the lack of descriptions and the relatively little attention paid by contemporary historians, who were too accustomed to periodic epidemic outbreaks, with later authors (Paulus Orosius, Eutropius, the Historia Augusta) giving historical character to that episode.

Equestrian statue of Marcus Aurelius
Equestrian statue of Marcus Aurelius. Credit: Jean-Pol GRANDMONT / Wikimedia Commons

The fact that cremation was the most common method for disposing of bodies means that the skeletons found in some mass graves—like the one in Gloucester, from which nearly a hundred bones were exhumed—are insufficient to determine whether they correspond to hurried burials due to the epidemic or to simple puticuli (common graves for the poor). This also prevents identifying the pathogen, which does not prevent most experts from leaning towards smallpox.

Galen, as we mentioned, is the one who left the most detailed description, which does not mean it is entirely sufficient or reliable. After observing many patients, he concluded that the ulcers they presented were a sign of recovery because they expelled the infected blood through them; consequently, he believed that the body healed itself and that one only had to avoid deterioration from scratching these ulcers. However, he also warned that only those of robust constitution would improve and the rest would have to be helped to cope with their illness with, for example, milk.

He also knew how to differentiate the Antonine Plague from the devastating plague that had ravaged Athens in the 5th century BC, during the Peloponnesian War, which Thucydides documented. Current science believes it has identified that Greek epidemic—which killed Pericles and his son—as typhoid fever, just as there seems to be a consensus to lean toward smallpox for the one in the 2nd century AD, despite Galen’s imprecision and the ignorance of microorganisms’ existence in his time. It is an illness that, indeed, causes sores and pustules on the skin, fever, and vomiting.

The problem is that genetic analyses indicate that the most severe form of smallpox emerged later, which is why typhus and hemorrhagic fever are also considered. Given that between 189 and 190, already during the reign of Commodus, son of Marcus Aurelius, a similar epidemic was documented that, according to classical historians Dio Cassius and Herodian, also spread throughout the empire—in the context of a great famine—it would be necessary to determine whether it was a new outbreak or something else. One proposed alternative is measles, also very contagious and with similar symptoms… but with the drawback that its origin is not dated until the 5th century AD.

The Angel of Death strikes a door during the epidemic in Rome (engraving by Levasseur based on a work by J. Delaunay).
The Angel of Death strikes a door during the epidemic in Rome (engraving by Levasseur based on a work by J. Delaunay). Credit: Wellcome Images / Wikimedia Commons

A succession of both could be the explanation for the marked virulence of the two epidemics; being different viruses (measles is caused by the Morbilivirus, smallpox by the Variola), it would have been impossible to generate antibodies between one and the other. The Croatian physician and philosopher Mirko Drazen Grmek, a scholar of the morbid reality of the ancient world, coined the concept of patocenosis to refer to a dynamic system where the manifestation of a disease depends on the presence and distribution of the set of diseases that are contemporary and characteristic of a particular population and space.

In that sense, those epidemic outbreaks and another later one, the so-called Cyprian Plague (which affected the empire between the years 249 and 269, without the descriptions left by the chronicler who gave it its name, Saint Cyprian, Bishop of Carthage, clarifying whether it was smallpox, flu, or some type of hemorrhagic fever like Ebola), would have been favored and worsened by a cooling of the climate that also led to greater environmental dryness and occurred in the 2nd century, according to a recent study.

The dates are significant and have led historians to consider the degree of impact that these plagues could have had on the crisis of the 3rd century and the decline of the Roman Empire. This is a historiographical debate that goes back a long way: the historian and philologist Barthold Georg Niebuhr (son of orientalist and explorer Carsten Niebuhr, to whom we dedicated an article), creator of the “critical historical method”, stated in his Römische Geschichte (“History of Rome”) that the reign of Marcus Aurelius was a turning point in many areas, and this was due to the plague.

American historian Kyle Harper, author of several books on antiquity in general and Rome in particular, agrees with him. In contrast, other specialists like Edward Gibbon and Mikhail Rostovtzeff disagree and believe that the Antonine Plague may have influenced the course of the empire but did not determine it, at least compared to political and economic factors.

The world in the 2nd century AD shows the Roman, Parthian, and Chinese (Han) empires.
The world in the 2nd century AD shows the Roman, Parthian, and Chinese (Han) empires. Credit: Thomas Lessman / Wikimedia Commons

Of course, it’s possible that the Chinese of the Han dynasty saw it differently. What do they have to do with this? some might wonder. To understand, one must talk about a Chinese scholar whose great obsession was the search for the Xianren, Enlightened Beings with extraordinary powers and very long lives (hence they were also called Immortals).

Ge Hong, an alchemist, physician, and Taoist master, recounts that in the years 151, 161, 171, 173, 179, 182, and 185, during the reigns of Emperors Huan and Ling, the Eastern Han Empire suffered up to seven epidemic outbreaks. Ge Hong lived at the turn of the 3rd and 4th centuries, so he did not experience that firsthand and merely narrates it, identifying the disease as smallpox. This has led some historians to suggest that it might have been the Antonine Plague since a Roman embassy visited the imperial court in the name of Andun, presumably a transliteration of the name Marcus Aurelius Antoninus (or perhaps of his predecessor, Antoninus Pius).

The journey of the Daqin delegation (as the Chinese referred to the Roman Empire) took place in the year 166, coinciding, as we have seen, with the spread of the plague in the West. Ironically, some authors place the origin of the infection in Central Asia (although Lucian of Samosata says it originally came from Ethiopia), from where it would have passed to Mesopotamia, Asia Minor, North Africa, and Europe before returning to its place of origin. In any case, it is possible that the impact of the Antonine Plague in China was reflected in a severe socioeconomic crisis and famines that led to social upheavals, such as the Yellow Turban Rebellion in 184.

To conclude, there is nothing better than to give the floor to Marcus Aurelius himself, one of those who wrote about the epidemic. He did so in his work Meditations with the Stoic tone that characterizes him:

Do you still prefer to breathe in vice, and
has experience not yet urged you to flee such a plague? For
the destruction of the intellect is a far greater plague than
a similar infection and alteration of the air that is spread
around us. For this plague is a feature of living beings, insofar
as they are animals; but that other plague is a feature of men,
insofar as they are men.


This article was first published on our Spanish Edition on September 13, 2024: Peste Antonina, la primera pandemia que asoló el Imperio Romano y que el médico Galeno intentó tratar con leche


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