In social psychology, hysterical contagion happens when people in a group appear to have physical symptoms or illnesses, even though these symptoms are actually caused by psychological and social factors.

Hysterical contagion is a strong type of social contagion. The symptoms may look like those found in medical conditions related to stress or mental health.

In 1977, Frieda L. Gehlen proposed a new idea about hysterical contagion. She suggested that what spreads among people is the belief that acting in certain ways can give them the advantages of being sick, such as receiving care or support. This choice might happen without the person realizing it. Gehlen’s idea is thought to better match what is already known about how contagion works and how groups behave together.

June bug epidemic

In 1962, a strange illness appeared in a dressmaking department of a US textile factory. People who worked there began experiencing symptoms such as numbness, nausea, dizziness, and vomiting. They believed an insect, called a "bug," was biting them and causing these symptoms. The news about the illness spread quickly among workers.

Soon, sixty-two employees showed these symptoms, and some were sent to the hospital. News reporters covered the situation. After investigations by doctors and experts from the US Public Health Service Communicable Disease Center, they concluded the illness was caused by mass hysteria.

Although some workers may have been bitten by an unknown insect, the researchers believed anxiety and stress were the main causes of the symptoms. No insect or spider that could cause these symptoms was ever found. Also, not all workers had visible bites.

Workers reported that the factory environment was stressful. The plant had recently opened, had a lot of work, and was poorly organized. Many of those who became ill also reported high stress in their personal lives. Social influences may have played a role in the spread of the illness.

Of the 62 employees who showed symptoms, 59 worked the first shift, 58 worked in the same area, and 50 of the 62 cases happened on two days after the media reported on the event. Most of the affected workers took time off to recover.