1. -Is a form of collective behavior involving
widespread anxiety caused by some unfounded belief

2. Dancing
Plague of 1518
The Dancing
Plague (or Dance
Epidemic) of 1518 was a case
of dancing mania that
occurred
in Strasbourg, Alsace (then
part of the Holy Roman
Empire) in July 1518.
Numerous people took to
dancing for days without rest,
and, over the period of about
one month, some of the
people died from heart
attack, stroke, or exhaustion.

3.  The Tanganyika laughter epidemic began on January 30, 1962, at a
mission-run boarding school for girls in Kashasha, Tanzania. The
laughter started with three girls and spread haphazardly throughout
the school, affecting 95 of the 159 pupils, aged 12–18.[ Symptoms lasted
from a few hours to 16 days in those affected. The teaching staff were
not affected but reported that students were unable to concentrate on
their lessons. The school was forced to close down on March 18, 1962
 After the school was closed and the students were sent home, the
epidemic spread to Nshamba, a village that was home to several of the
girls.In April and May, 217 people had laughing attacks in the village,
most of them being school children and young adults. The Kashasha
school was reopened on May 21, only to be closed again at the end of
June. In June, the laughing epidemic spread to Ramashenye girls’
middle school, near Bukoba, affecting 48 girls. Another outbreak
occurred in Kanyangereka and two nearby boys schools were closed.

4.  http://en.wikipedia.org/wiki/Mass_hysteria#Dancing_
Plague_of_1518