It is a diagnosis that doctors are usually hesitant to make, concerned they might miss any other cause and uncomfortable with 19th-century images of screaming girls, trances or collective delusions.
But Dr. Víctor Manuel Torres Meza, the director of epidemiology for the Mexico State health department, said there were some 80 documented cases from around the world. They are usually in closed communities, like schools and factories, and they tend to occur more frequently among adolescents and among girls.
“We have a group of only girls living under a situation of strict control and discipline that they have to follow to the letter,” Dr. Torres Meza said. “These illnesses occur in closed groups that have no external communication. Emotional factors have a cumulative effect. What is the trigger?”
