It is not known in detail how people got infected, but it seems that Scarabs' eggs were ingested by humans with their food. The scarab grubs grew, pupate and enclose inside the body, eventually killing the host, releasing the bugs.
The plague started in the city of Fahranur and wiped out almost the entire population of Istan, among them the last of the Primeval Kings. Thereafter the island was abandoned for more than 60 years, until a new human settlement was established in 720 DR.
The plague also spread to other parts of Elona, but didn't have quite the devastating effect that it had in Istan.
In the quest chain started by A Perplexing Plague the player is sent to investigate the origin of the plague. A historic journal describes the event:
- "This plague is tearing the city apart. It seems to strike without any sort of logic...young and old alike are devastated by its effects. Those who still survive burn down entire buildings in hopes of cleansing the plague's dire corruption, but it seems hopeless. Word has reached me of a terrible new stage of this plague, and people are claiming that bugs escape from within the boils. I hope that these are only delusions brought on by the plague's effects, but I am beginning to wonder if it could be true...."