A previous outbreak of mass hysteria, in 2003, affected at least 60 people in Raití, northern Nicaragua (Image: La Prensa)

An outbreak of mass hysteria is reported to have struck three indigenous communities living near the river Coco in northern Nicaragua. A total of 43 people have reportedly fallen ill with what is known locally as grisi siknis (“crazy sickness”).

Doctors, anthropologists and sociologists who have studied previous cases of mass hysteria – also known as mass psychogenic illness – have so far failed to come up with any clear explanation for the phenomenon.

Linda Geddes spoke to Elie Karam of St George Hospital University Medical Centre in Beirut, Lebanon, who studied an outbreak of mass hysteria in Lebanon during 2004, to discover what we currently know.


What are the typical symptoms?

The first group can be summarised as anxiety symptoms: tremors, shaking, difficulty breathing and feelings of suffocation. The second type is referred to as a dissociative symptom: the person does not recognise where he or she is, seems to be in a trance, looks as if they are in a daze, etc.

Younger individuals, and females, are more likely to be affected.

How often do outbreaks of mass hysteria occur, and are they becoming more common?

There is no real way of saying how common they are. The phenomenon seems to have been going on for centuries. It is believed that many collective behaviours attributed to witchcraft could be due to mass hysteria.

Dissociative symptoms seem to be more common in less industrialised societies, whereas the pure anxiety symptoms are more common in industrialised ones. The crucial point is that symptoms appear to be contagious. Usually, the sufferers have had a high level of communal stress.

Is the Nicaragua outbreak particularly large and unusual, or is it fairly typical?

The outbreak seems to be on the large side, but not huge. We need more data about the way this outbreak spread. Usually the symptoms start with one person; typically they are reported to occur in individuals who are in the line of sight of the “trigger” case. For Nicaragua we don’t know yet.

Does anyone understand what causes the phenomenon, and is there any physiological explanation?

In short, no. Explanations of the causes vary with the settings. Demonic interference can be ruled out, but so can more recent purported explanations that point to pollution.

Is there a cure?



Not as such. Symptoms always abate within a few weeks. Reassuring the community to reduce fear is key, as is keeping publicity and media attention to a minimum.