Listening to the public radio show Radio Lab this afternoon, I heard this segment on "laughing sickness" in Tanzania (the segment's a re-broadcast from February). Back in the 1960s, girls in a boarding school suffered from an unexplained outbreak of laughter, a kind of mass hysteria that quickly overtook the school. They couldn't control it, and no one could explain it. The laughing sickness spread throughout the countryside and lasted for quite a while.
A producer from the show recently went back to the country to try to unravel the mystery after forty years. She discovered that whatever causes people to suffer from attacks of prolonged laughter still occurs. She spoke to a woman who as a six year old suffered from the hysteria, surprisingly far from the school, but where some of the girls who attended it lived. Like many others, the girl's mother decided to go to the local witch doctor for a cure. The witch doctor suggested the cause was the souls of angry dead caterpillars. The interviewee, however, rejected this explanation, telling the producer she thinks it might have been bacteria or some other scientific cause.
By following such leads, the producer comes up with this explanation. What's interesting about the period in question, she points out, is that the outbreak occurred just around the time of Tanzanian independence, when people were under tremendous psychological stress. Further, as a local assistant to a witch doctor who was present at the time of the outbreak told her, churches were busily competing for the allegiances of the citizenry. I'd suggest this creates more stress, particularly for those who had been used to traditional (non Western) religious practices. As the producer says, the first girl who started laughing uncontrollably represented her nation--she went a little nuts under all the pressure. There are likely to be bumps in the road for any young person coming into adulthood, and any nation joining the world community. For more about mass hysteria in school settings see this article from the Guardian dated 2007
See also Christian F. Hempelmann, The laughter of the 1962 Tanganyika ‘laughter epidemic’, 20 Humor: International Journal of Humor Research 49-71 (2007).
Here's the abstract provided for Mr. Hempelmann's article. "The present article discusses the role of laughter in the much cited ‘laughter epidemic’ that occurred in Tanganyika in 1962. Despite its extraordinary nature, the veracity of the event is confirmed, crucially on the basis of similar reports. But most current representations are flawed by their exaggeration and misinterpretation of the role of laughter in the event, relating it to a humorous stimulus, a virus or environmental contaminant, or identifying it as contagious laughter. It is argued that the event is a motor-variant case of mass psychogenic illness of which laughter is one common symptom. Therefore it cannot serve as support for other arguments in humor research."