On 30 January 1962, a laughing epidemic broke out in a village in Tanzania that has been estimated to have lasted anywhere between 6 and 18 months. An uncontrollable wave of laughter swept through a local school, eventually spreading across much of the local region. 14 schools were forced to shut down and several hundred people were affected, with symptoms ranging from simple laughter to fainting, rashes and respiratory problems.

Sources: one, two

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