What was the 1962 Tanganyika laughter epidemic?

The Tanganyika laughter epidemic was an outbreak of mass hysteria, now usually called mass psychogenic or sociogenic illness. It began at a mission-run boarding school for girls in Kashasha, near Lake Victoria in what is now Tanzania, and spread to nearby schools and villages. The physicians who documented it, A. M. Rankin and P. J. Philip, found no infectious or toxic cause and judged mass hysteria the most likely explanation. [1] [2]

According to the 1963 report in the Central African Journal of Medicine, the disease began on 30 January 1962, when three pupils started behaving abnormally and it spread rapidly through the school. Of 159 pupils aged 12 to 18, 95 were affected before the school closed on 18 March. When it reopened on 21 May, 57 pupils were affected before it closed again at the end of June. None of the teaching staff was affected. [2]

The outbreak then followed the girls home. About ten days after the first closure it appeared at Nshamba, 55 miles west of Bukoba, where 217 of roughly 10,000 people were affected in April and May. In June, 48 of 154 girls at Ramashenye school fell ill, and the village of Kanyangereka was affected after a sick pupil was sent home. Wikipedia reports that 14 schools were shut and about 1,000 people affected, and that it died out about 18 months after it began. [2] [1]

Attacks of laughing and crying lasted from a few minutes to a few hours, followed by a respite and then a recurrence. They came with restlessness and sometimes violence if the person was restrained. Some patients said things were moving around in their heads or that someone was chasing them. Symptoms lasted from several hours to 16 days, no deaths were reported, and most sufferers were adolescent schoolchildren and young adults. The authors noted that no literate, relatively sophisticated people, such as teachers, policemen or village headmen, were attacked. [2]

Physical examination found no fever or other notable signs beyond frequently dilated pupils and exaggerated leg reflexes. Lumbar punctures in 17 cases were normal, and blood from active cases grew no virus and showed no viral antibodies. No food factor was found. The authors could not explain why the outbreak started, and said that once begun it could spread without the original trigger. [2]

Rankin and Philip said they could not identify a precipitating cause, and questioning of the girls produced no reason. Later researchers have proposed stress as a background factor. Christian Hempelmann, a linguist at Texas A&M University, has suggested that the episode was stress-induced, pointing to Tanganyika's recent independence and to students' reports of pressure from the higher expectations of teachers and parents. Atlas Obscura adds the unfamiliar demands of British-run schools. These are proposed explanations rather than established causes, and the original report did not confirm them. [2] [1] [3]