Here in the first book of the Iliad we have the earliest description in Greek literature of the impact of epidemie disease. The poet describes how Apollo, angered by Agamemnon's arrogant treatment of his priest, who had come to the Achaean camp to ransom his daughter, sent in punishment a plague upon the army investing Troy. At this time, Celsus says 'Diseases were attributed to the wrath of the gods' (De medicina, Proem, 4). Eventually, the Achaeans, at the suggestion of Achilles, consulted the soothsayer, Calchas, who revealed to them that Apollo had sent the disease to avenge his priest and that the god would not lift the pestilence until the girl had been returned to her father, without ransom and with a hecatomb of oxen for sacrifice. The Achaeans complied, cast the 'defilements' into the sea and sacrificed to Apollo. The god was placated and the plague abated.

Here in the first book of the Iliad we have the earliest description in Greek
literature of the impact of epidemie disease. The poet describes how Apollo,
angered by Agamemnon's arrogant treatment of his priest, who had come to
the Achaean camp to ransom his daughter, sent in punishment a plague
upon the army investing Troy. At this time, Celsus says 'Diseases were
attributed to the wrath of the gods' (De medicina, Proem, 4). Eventually, the
Achaeans, at the suggestion of Achilles, consulted the soothsayer, Calchas,
who revealed to them that Apollo had sent the disease to avenge his priest
and that the god would not lift the pestilence until the girl had been
returned to her father, without ransom and with a hecatomb of oxen for
sacrifice. The Achaeans complied, cast the 'defilements' into the sea and
sacrificed to Apollo. The god was placated and the plague abated.