The Early Medieval Pandemic began in 541 with the Justinianic Plague (Yersinia pestis) and continued through the 8th century. Today, echoes sound from the accounts of Procopius (c. 500 to after 565), Evagrius Scholasticus (born c. 536) and John of Ephesus (c. 507–588).

The historian Procopius says that pestilence embraced the entire world and blighted the lives of all men, respecting neither gender nor age, attacking at all times of the year, starting in Egypt, then to Palestine and on to the land of the Persians and barbarians (Dewing 1914). There was sudden fever, and within days a bubonic swelling developed in the groin or elsewhere. Some became comatose, forgot those familiar to them and seemed to be sleeping. If anyone cared for them, they would eat without waking; but some were neglected, and they died through lack of sustenance. Others developed delirium, with insomnia and distorted imagination: they suspected men were coming to destroy them, and would rush off in flight, crying out. Those attending them were in a state of constant exhaustion and had a most difficult time of it. Work of every description ceased, and in a city abounding in good things starvation ran riot.

Evagrius, scholar and intellectual, describes being seized with buboes while still a schoolboy, and losing by recurrence of the plague at different times his wife, several children, many kin, as well as domestic and country servants; not quite 2 years before writing, now in his 58th year, on its fourth visit to Antioch, he lost a daughter and her son (Walford 1846). Manifestations were various. Some died after 2 or 3 days, in possession of their mental and bodily powers. People who had been attacked once and twice and had recovered, died by a subsequent occurrence. Some perished by living with the infected; by touching them; by having entered their chamber; or by frequenting public places. Some fled infected cities but imparted the disease to the healthy. Some were free from contagion, although they had associated with many afflicted in sickness and death. Some who desired death, on account of the loss of their children and friends, placed themselves as much as possible in contact with the diseased, but nevertheless were not infected.

John of Ephesus was a Byzantine historian. Much of his Ecclesiastical History is missing but part appears in the Chronicle of patriarch Michael the Syrian (1126–1199) (Chabot 1899). John was living in Constantinople when the scourge fell: ‘men became enraged, like dogs, went mad, attacked each other, went into the mountains and committed suicide’. It raged among the poor; there were days when 5000 were carried away, others 7000, others 12 000, and up to 16 000 in one day; over 300 000 were taken from public places. When those of low rank were dead, the devastator stretched out his hand over the mighty; not forgetting animals and reptiles.