Somewhat related to the above is choreomania. Also called dancing mania, dancing plague, St. John's Dance and St. Vitus's Dance, choreomania was the sudden onset of erratic dancing that would sometimes "infect" thousands of people at a time, making them dance erratically, sometimes to the point of death. This "plague" occured between the 14th and 17th centuries C.E., and the cause is still generally unknown.