Choreomania:
[en.wikipedia.org]
Given none of the people had autopsies performed it did not spread through all of the population and there have been no occurrences in recent times I am going with the increase in sanitations and hygiene have removed the cause.
Some virus or bacteria that affects the brain or nerves. I get restless leg syndrome sometimes (got it once the night of my knee surgery it was awful and the nurses could do nothing about it) Walking helps relieve it.