In 1962, some girls at a school in Tanganyika, now Tanzania, started laughing and could not stop. Soon more than half of the students had the same problem, so the school closed. When the girls went home, people in their villages started laughing too.

But it was not happy laughter. Some people also cried, ran around or fainted. Doctors found no virus or poison. Today, experts think stress was the real cause.

The so-called "laughter epidemic" began in January 1962 at a girls' boarding school in the Bukoba district of Tanganyika. According to two local doctors, Rankin and Philip, a few students began laughing, and the attacks soon spread to more than half of the pupils, forcing the school to close. When the students returned to their villages, family members and neighbors were affected as well, and around 1,000 people were reportedly involved in total.

However, the attacks were not about humor. People also cried, ran around restlessly or fainted, sometimes for hours. Tests found no infection or poison. Researchers now see the event as mass psychogenic illness, in which ongoing stress produced real physical symptoms.

In 1962, pupils at a girls' boarding school in the Bukoba district of Tanganyika began having attacks of laughter. The event is often retold as proof that laughter is contagious, but the record points somewhere else. The first report, by the physicians Rankin and Philip, says the attacks affected more than half of the school's pupils and later spread to villages as the students went home.

Around 1,000 people were eventually said to be involved. The laughter came with crying, restless running, occasional violence and fainting, and the episodes could last for hours and come back. No infectious agent or toxin was found. In 2007 the humor researcher Hempelmann argued that the outbreak was a motor form of mass psychogenic illness. The psychiatrist Wessely had linked this category to symptoms that spread gradually under prolonged tension.

Some scholars point to strict school discipline and rapid social change after independence, though these are later interpretations that cannot be tested. A diagnosis of this kind is reached by ruling out other causes, and testing in 1962 was limited, so some doubt is unavoidable. Hempelmann also warned that the story has been exaggerated as it was passed along.