Vengson's Fever

The core society of Hexbahn was struck by a most unusual magical plague. The symptoms emulated those of the spell 'irresistible dance' in that those who contracted the condition feel inescapably compelled to dance ceaselessly. What made the matter so dire was two problems, first was that the condition was contagious spending too much time observing someone dancing due to the condition would cause it to infect you as well, the second was unlike the spell the condition didn't end after a set interval so you would literally dance yourself to the point of exhaustion and eventual death.
All sufferers of the condition described hearing the same song blaring in their ears, driving them dance despite no sounds heard by outside observers. In fact one of the earliest ways to tell a person was beginning to catch Vengson's Fever was that they'd begin to hear the music first at a low volume in the background before it rapidly ramps up and the effects fully take hold.
The condition was ultimately dealt with by tracking down "patient zero" a gentleman named Vengson, while research into how and why are still ongoing he was identified as the source of the condition and the music that drove it. He himself was immune to the detrimental effects, a 'Typhoid Mary' scenario where he could spread it for the rest of his life. The 'cure' was to ban Mr. Vengson from ever dancing again, without his dancing the music in others eventually faded and the spread was contained though many who were too far along were lost before the effect could be broken.

Transmission & Vectors

Proximity to someone already infected, observing their symptoms (dancing) for too long.

Causes

The origins within Mr. Vengson are still yet to be determined, how or why his dancing causes this infectious condition in others is something that will be studied for years to come.

Symptoms

Loud music blaring in their ears that only they can hear, and an irresistible compulsion to dance ceaselessly.

Treatment

Stopping the source of the music (Mr. Vengson) and isolating those already infected to prevent wider spread while the effects dissipate.

Prognosis

Without intervention suffers will ultimately dance themselves to death, which is what made the condition so dangerous.

Affected Groups

The full spectrum of the population was susceptible, regardless of any delineating features such as age, race, or gender.

Hosts & Carriers

Mr. Vengson is inexplicably the originating source/host of this condition.

Prevention

Lifetime ban against Mr. Vengson dancing ever again. Anyone who begins to hear sourceless music is advised to notify authorities and immediately self-isolate.

Cultural Reception

Initially thought to be a harmless if silly enchantment, the cultural reception of the condition quickly shifted first when they realized no one could stop and second when people started dropping dead from it.

Type

Magical

Origin

Magical