TIL that in 1518 there was a outbreak of a 'dancing plague' in Strasbourg, in which hundreds of people inexplicably danced for weeks on end, claiming lives of victims along the way…

https://en.wikipedia.org/wiki/Dancing_plague_of_1518

https://www.reddit.com/r/todayilearned/comments/156vk73/til_that_in_1518_there_was_a_outbreak_of_a/