Day 2 of my 28 Monsters Challenge.

A monster that spreads a specific disease.

The coulrhythm is an eternally dancing entity that travels to small towns and villages and beckons the townspeople to join it in its dance. Once someone accepts its offer to dance the person will have an intense compulsion to dance nonstop until they either die or pass our from exhaustion. Anyone witnessing this person's dance will begin to feel similar compulsions.

It is thought to be the cause of many instances of dancing mania.