It is said that laughter is infectious. In 1962, an extreme case of “laughter infection” happened in village in Tanzania. The phenomenon originated in a boarding school for girls. On January 30, three girls spontaneously burst out in laughter and could not stop themselves from laughing. Soon after, the whole class was suffering from fits of uncontrollable laughter. The “infection” then spread throughout the school, claiming 95 of the 159 students over a stretch of two months. This strange symptom of uncontrollable laughter lasted anywhere from a few hours to 16 days. Interestingly, teachers were not affected and only girls between the ages of 12 to 18 were affected. By March 18, the school was forced to close down due to students not being able to focus during class.
The laughter epidemic was not localised to the school. After the school shut down and the girls returned home, fellow villagers were afflicted by the laughing disease, resulting in 217 villagers being “infected” by May (mostly children and teenagers). By June, the laughing epidemic spread to another nearby school, affecting 48 girls. The epidemic then went on to claim two more schools, forcing them to close down. By the time the epidemic died down (6 to 18 months after “patient zero”), it had affected over a 1000 people and shut down 14 schools.
So what was this strange disease? Was it some new viral infection causing neurological symptoms? Was it a toxin in the water supply? The answer was even simpler: mass psychogenic illness, also known as mass hysteria. Mass hysteria is a psychological phenomenon that occurs in groups placed in high-tension situations, such as within an airplane. This setting is perfect for triggering a mass delusion, causing the person to believe they are suffering from a physical disease. The trigger is usually another “patient” and the hysteria spreads like wildfire, usually by people seeing affected victims. Although the above case makes mass hysteria look like a harmless, amusing phenomenon, psychosomatism (when the mind tricks the body into thinking it is sick) can cause symptoms such rashes, fevers, vomiting and even paralysis. In fact, all of these symptoms were also reported during the Tanganyika laughter epidemic.