"CONTAGIOUS laughter. Consider the bizarre events of the 1962 outbreak of CONTAGIOUS laughter in Tanganyika. What began as an isolated fit of laughter (and sometimes crying) in a group of 12- to 18-year-old schoolgirls rapidly rose to epidemic proportions. CONTAGIOUS laughter propagated from one individual to the next, eventually infecting adjacent communities. The epidemic was so severe that it required the closing of schools. It lasted for six months"

(Provine 1996)