AD 165

Antonine Plague

First attested phase of the Antonine epidemic in the Roman East

The earliest possible witness was not a soldier at Seleucia but an orator who nearly died outside Smyrna.

165 in the East, 166 at Rome

An illness the orator Aelius Aristides described near Smyrna in the summer of 165 is a possible early firsthand instance of the epidemic later called the Antonine Plague. The association is plausible but not certain.

Ancient narratives also tie the pestilence to Roman operations at Seleucia in Mesopotamia in the winter of 165–166, though that tradition does not securely establish where the pathogen came from.

The epidemic is securely placed at Rome only in 166, when returning forces from the Parthian campaign were understood to have carried the infection westward.

Two stages compressed into one

So the claim that the pandemic “breaks out in Rome” in 165 folds together eastern evidence from 165 and the Roman outbreak of 166. There was no single identifiable outbreak day in either year.

Galen encountered the epidemic at Rome and then left the city for Pergamum; by 168–169 he was observing epidemic illness among troops in northern Italy. He described survivors developing a dark, ulcerated rash over the body around the ninth day.

What “plague” does not mean here

The word means pestilence. It does not identify bubonic plague caused by Yersinia pestis, and the diagnosis remains open: Galen’s descriptions strongly resemble smallpox, but no ancient DNA from a securely identified victim has confirmed the pathogen.

No reliable empire-wide mortality total exists either. Figures such as five to ten million deaths are model-dependent estimates, not ancient counts.

Sources

Researched 23 Aug 2026 6 sources 2 audit passes Date disputed

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Date disputed. Sources disagree; the research places it at ~0165.

What the sources leave uncertain

The label covers a prolonged epidemic rather than a one-day event.
The association of Aristides's illness with the Antonine Plague is plausible but not certain.
The diagnosis remains debated. Galen's descriptions strongly resemble smallpox, but no ancient DNA from securely identified victims has confirmed the pathogen.
No reliable empire-wide mortality total exists.