Outbreaks of mass psychogenic illness (MPI) or mass hysteria are common social phenomena worldwide, and Mexico has been no exception. This pathology has been defined as a group of physical signs and symptoms that suggest the presence of an organic disease but no clinical evidence or support in specific laboratory studies¹. In our setting, it is known only through the written press or through dissemination in social networks; in the Mexican medical literature, there is a striking lack of reports or formal research, which has led to a deficiency of epidemiological, clinical and psychological-psychiatric knowledge of these crises.

MPI is characterized by the rapid spread of signs and symptoms of illness within a cohesive group, such as schools and workplaces; it predominantly affects females, and its transmission is thought to be purely visual². Headache, dizziness, nausea, and abdominal pain are the most common symptoms reported in the literature³.

In 2006, after playing with a Ouija board, a group of teenage students in a town in southern Sonora presented with fainting, nausea, headaches, and laughing for no apparent reason. Hypotheses of stress, divine punishment, infection, or food poisoning soon followed. The crisis assessment by Gregorio Katz, a child psychiatry pioneer in Mexico, concluded that it was a "collective hysteria of conversive type" caused by emotional factors in those adolescents⁴.

More recently, in October 2022, slightly more than 100 adolescents from three high schools in two cities in Chiapas presented with mysterious symptoms diagnosed by the authorities as secondary to cocaine intoxication. However, this condition was not confirmed during the hospitalization and examination of several dozen of those affected⁵. To this day, the outbreak´s characterization, evolution, and outcome have been forgotten.

Admittedly, the root cause of MPI is still unknown. However, a recent study identified some predisposing factors, including cleanliness and safety at school, and previous psychological trauma⁶. In contrast to other authors⁷, this study did not find an association with depression and anxiety scores in the studied school population. However, these circumstances should be kept in mind in the face of the confinement and social distancing for the control of the COVID-19 pandemic.

Doubts about the etiology of MPI usually lead to great concern among families, and educational and health authorities. In this regard, personal factors have been associated with this entity, such as personal demotivation, emotional maladjustment, and loss of cultural values.

The first step in controlling MPI falls to the epidemiological authorities and local medical services; early identification of social conditions and psychological stress in adolescents, symptomatic or not, are part of the multidisciplinary study to guide a rapid therapy to prevent further audiovisual spread. In addition, the diagnosis and management of outbreaks provide reassurance to the families of those affected and to the general population. On the contrary, withholding information and not adequately disclosing the results of the study of these events leads to greater social unrest.

Finally, a proper documentation and scientific dissemination of the investigation of each case of MPI is the duty and obligation of health authorities. This research would undoubtedly contribute to the epidemiological and medical knowledge and, above all, to identifying the socio-psychological and psychiatric precipitating factors of our young people³.