Mass Psychogenic Illness – How to Survive a Panic Epidemic

Originally published in United Academics Magazine on January 6, 2012.

Also known as Mass Psychogenic Illness (MPI), mass hysteria is an underreported and contentious diagnosis that mirrors the prominent social concerns of an era. From possessed nuns in the middle ages to environmental contamination and terrorism scares today, here is a peek into our collective angst through the years.

A female news agency employee suddenly collapsed in the Virgin Blue terminal of Melbourne’s Tullamarine airport one morning in 2005. After she was taken to the hospital, two other employees collapsed and security guards and airline staff felt dizzy, nauseated and had respiratory problems. Some noticed a strange odor. By mid afternoon the terminal had been evacuated, 47 people had been transported to the hospital and medical personnel wearing protective suits and masks were treating victims still at the scene. Air samples had been taken by the local and metropolitan fire brigade but no suspected agents were fond in the air. By early evening, all of the casualties, aside from one with pre-existing asthma, were released from the hospital and emergency services declared the area safe again. The shut down lasted eight hours, 60 Virgin Blue flights were cancelled, 14.000 passengers were stranded and business cost estimates ran into the millions of dollars.

Symptoms without organic basis

Although government officials referred to the Melbourne incident as a “mystery illness”, Australian sociologist Robert Bartholomew thinks it was most likely a case of mass psychogenic illness. A proliferate writer on the subject, he defines mass psychogenic (or sociogenic) illness as the rapid spread of illness signs affecting members of a cohesive group, caused by psychological distress with no organic basis. Dominant symptoms include headache, dizziness or light-headedness, nausea, abdominal pains, cough, fatigue, drowsiness or weakness, and a sore or burning throat.

Bartholomew studied hundreds of cases, from demon possessions in nunneries in the Middle Ages to the Belgian Coca-Cola contamination scare in the 90’s and the “Bin Laden Itch” after September 11, 2001. (This last case involved thousands of US school students reporting an array of rashes following anthrax attacks). He argues that MPI is an underreported problem and that it is not a diagnosis of exclusion as some believe. Together with British psychiatrist Simon Wessely, he identified a list of characteristic features.

Characteristics of Mass Psychogenic Illness

  • Symptoms with no plausible organic basis
  • Transient and benign symptoms
  • Rapid onset and recovery
  • Occurrence in a segregated group
  • Extraordinary anxiety
  • Symptoms spread via sight or sound (seeing or hearing of another ill person causes symptoms)
  • Beginning with older or higher-status persons and then spreading to younger or lower-status persons
  • A preponderance of female participants*

* It is not yet clear why 85% of MPI victims are women but Bartholomew and colleagues suspect social and cultural reasons like women’s perceptions of inferiority in certain contexts, differences in stress coping strategies and differences in treatment seeking behavior.

Bartholomew and Wessely also discovered a fascinating correlation between MPI and the prominent social concerns of the times. Prior to 1900, incubated in a tense atmosphere in convents, schools and factories, predominant motor symptoms like dissociation, melodramatic acts of rebellion, shaking, twitching and contractures could persist for weeks or months. Twentieth-century reports feature anxiety symptoms that are triggered by a sudden exposure to, most commonly, an innocuous odor or food, air or water poisoning rumors. From the early 1980s to the present, especially since the September 11 terrorist attacks in the US, there has been an increasing focus on chemical and biological terrorism.

Mass psychogenic illness mirrors the prominent social concerns of the times – here are some examples:

Possessed nuns
1491 (Cambrai, France): It was reported that a group of nuns in a convent ran across the fields like dogs, climbed on the trees and hung from their branches like cats and imitated the voices of different animals. (Certain animals were considered to be potential demonic familiars). It is believed that the recipe for this outbreak – and many similar ones in other European convents – were exceedingly strict Christian religious orders at the time, coupled with a popular belief in witches and demons.

Convulsing factory workers
1787 (Lancashire, England): One male and 23 female workers experienced violent convulsions and sensations of suffocation in a cotton mill. It is believed that during the industrial revolution, harsh working conditions and weak or non-existent labor unions triggered outbreaks like these in oppressive western job settings, typically factories.

Coca-cola poisoning scare
1999 (Belgium): 33 pupils at a secondary school experienced nausea, stomach pain, breathing difficulty, dizziness and lightheadedness shortly after drinking containers of Coca-Cola. In hospital no abnormalities were found but the incident made headlines across Europe. The following day 75 schoolchildren at four other schools claimed similar ill effects and the Belgian Poison Control Center received almost a thousand phone calls concerning symptomatic subjects. This led to a nine-day country-wide ban on Coca-Cola products but no credible contamination of the cans was ever found. The episode coincided with the “dioxin crisis”, a major Belgian food scare leading to a massive recall of chicken, eggs, dairy and meat products.

Subway station substance
2001 (Maryland, USA): After the September 11 terrorist attacks of 2001, a man sprayed a mysterious substance into a subway station, resulting in 35 persons being treated for nausea, headache and sore throats. The fluid was later identified as a common, harmless window cleaner.

Moreover, when Bartholomew and Wessely looked for social and psychological similarities among the victims, they could not find any. Studies on possible predispositions like extroversion, paranoia, absenteeism at work, academic performance and IQ- all turned out inconclusive. It seems that nobody is immune to MPI.

A sensitive label

A psychogenic cause for symptoms can be difficult to accept for victims and community members, many who resent the “mass hysteria” label. Mass hysteria is typically viewed as something that happens to others. For this reason, cases are often officially left unresolved under the guise of the label “mystery illness”.

According to Bartholomew and Wessely, this also happened in the “Toxic Bus” case in Canada. They write that, in 2004, just before leaving a public bus in Vancouver, a Middle Eastern looking passenger asked the bus driver how his day was going. When the bus driver said “good”, the man said “it won’t be for long”. Shortly thereafter the bus driver felt nauseated and vomited and one of the passengers felt ill as well. When the driver radioed for help, fearing a chemical or biological attack, the two responding paramedics fell ill, as did others arriving on the scene. 19 people were briefly quarantined but air quality tests and a forensic examination of the bus were unremarkable. Afterwards, Vancouver’s Chief Medical Health Officer concluded that the cause of this event was mass anxiety, but both police and ambulance agencies did not accept this. They hired a private firm for additional testing and later came up with an improbable theory designating methyl-chloride gas, measured in minute quantities on the scene, as the culprit in the “attack”. They could not accept the idea that experienced medical professionals would have succumbed to mass hysteria.

Diagnostic labels clearly matter. Army psychologist Ross Pastel studied the effects of weapons of mass destruction on mass hysteria and wrote that the U.S. military’s use of words like “shell shock” and “combat exhaustion” had an effect on both prognosis and treatment. “Terms such as ‘war neurosis’ or ‘psychoneurosis’ had a stigma of mental illness and had a poorer prognosis, but terms such as ‘combat exhaustion’ suggested a normal reaction to an abnormal stimulus and gave a positive expectation of recovery and return to duty following a short respite from the war,” Pastel wrote. For that reason he prefers the term “outbreaks of multiple unexplained symptoms” over mass hysteria or mass psychogenic illness.


To best deal with future cases of MPI, Bartholomew and Wessely have suggested a checklist with practical steps for law enforcement and other emergency service personnel. Their advice includes calm, firm and confident leadership, not telling patients that it is “all in their heads” as the symptoms that they are experiencing are real, separating the patients from non-patients and avoid prompting patients as to what their symptoms should be but rather let the patients disclose their symptoms without guiding them.

“Preventing future episodes is problematic as outbreaks are always morphing to take new forms,” Bartholomew” stated. “Only the form changes to reflect social and cultural conventions. In the past, episodes were driven by the fear of witches and demons; today it is toxic odors and terrorists.”

Clearly mass psychogenic illness remains a fascinating interaction between our brain and body. Where the placebo effect in medicine has shown us the power of belief to make us better, MPI is one of the ways a belief can make us sick.

The War Of The Worlds broadcast and the Martian invasion panic

In 1938, the radio drama broadcast “The War of The Worlds” about an alien invasion by Martians, frightened a large number of American listeners who believed the faked news reports were real. Robert Bartholomew wrote a number of books and articles on this famous incident and called this a case of “social delusion”, not “mass hysteria”, because it involved false or exaggerated beliefs but no illness symptoms. “It is a testament to the remarkable power of expectation on perception,” he wrote and he described eyewitness accounts of people actually smelling the Martian’s poisoned gas, feeling the heat rays as described on the radio and hearing machine gun fire and the “swish” sound of the Martians. “Not only does the Martian panic demonstrate the enormous influence of the mass media in contemporary society,” he wrote, “but in recent years an ironic twist has developed. “Sensationalist reporting by the same mass media after the event, he argued, caused people to believe that the panic caused by the broadcast was far more extensive than it really was. Studies have shown by now that, instead of more than a million panic-stricken Americans, there were probably no more than a few thousand.


Bartholomew, R. & Wessely, S. (2002). Protean nature of mass sociogenic illness: From possessed nuns to chemical and biological terrorism fears. The British Journal of Psychiatry, 180, 300-306. DOI: 10.1192/bjp.180.4.300

Bartholomew, R. & Wessely, S. (2007). Canada’s “Toxic Bus”: The New Challenge for Law Enforcement in the Post-9/11 World/Mass Psychogenic Illness Canadian Journal of Criminology and Criminal Justice/La Revue canadienne de criminologie et de justice pénale, 49 (5), 657-671. DOI: 10.3138/cjccj.49.5.657

Pastel, R. H. (2001). Collective behaviors: mass panic and outbreaks of multiple unexplained symptoms. Military medicine, 166 (12 Suppl), 44-6 PMID: 11778431

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