A relatively recent example of MPI occurred at the Warren County High School in McMinnville, Tennessee. At the time, the school had 1,825 students and 140 staff members. On November 12, 1998, a teacher believed she smelled gasoline, which caused her to complain of headache, shortness of breath, dizziness, and nausea. Seeing her response, some of her students soon developed similar symptoms. As the classroom was being emptied, other students, observing what was happening, began to report feeling unwell too. A schoolwide fire alarm was activated, and the school was evacuated. The teacher and several students were transported by ambulance to a nearby hospital, in full view of other students and teachers who were outside because of the alarm. Large numbers of police, firefighters, and emergency medical personnel from three counties responded. A total of one hundred people went to the hospital that day, and thirty-eight were admitted. Classes were canceled.
The school was closed for four days. It was inspected by the fire department, the gas company, and state officials from the Occupational Safety and Health Administration (OSHA), but no problems were identified. After the school had been deemed perfectly safe, the students and the teachers were allowed to return. Unfortunately many still smelled odors, and on November 17, seventy-one people were stricken. Ambulances were again called, and the school was evacuated and then closed.
The school’s principal was fed up. In a “no more Mr. Nice Guy” move, he decided to call several government agencies, including the famed Epidemic Intelligence Service of the Centers for Disease Control (CDC). Also involved were the federal Environmental Protection Agency, the Agency for Toxic Substances and Disease Registry, the National Institute for Occupational Safety and Health, OSHA, the Tennessee Department of Health, the Tennessee Department of Agriculture, and numerous other local emergency organizations and personnel. The investigation was extremely thorough. Aerial surveillance identified potential environmental sources of contamination; personnel explored caves in the vicinity of the school; the school’s air-handling, plumbing, and structural systems were thoroughly checked; core samples were drilled from the grounds around the school; and air samples (including from the days of the outbreak) and water and waste samples were tested. The air was evaluated with an astonishing array of technology, including colorimetric tubes, flameionization detectors, photoionization detectors, radiation meters, and combustible-gas indicators.
Two years later, a New England Journal of Medicine article described the extensive examination of possible environmental causes for the illness and reported the results of the investigation by the CDC. In the end, like Rankin and Philip studying the African laughter epidemic, the investigators concluded that psychogenic factors were to blame. They found that the illness was associated with directly observing another ill person during the outbreak and with being female.12 The diagnosis was epidemic hysteria.
This diagnosis did not sit well with the community, and it upset many of those who had been ill, such as one twelfth grader who was quoted as saying, “They said we were crazy…. It just made me mad. When I’m sick, I don’t want someone to say I’m faking. They wouldn’t have taken me to the hospital, and my blood pressure wouldn’t have been sky-high, if I wasn’t sick.”13 Of course, the symptoms of those with MPI. whether laughing, dancing, fainting, or nausea, are quite real; they do not “fake” their experience in the deliberate, premeditated way that a malingerer does. The astonishing reality is that our own anxiety makes us sick, but so does the anxiety of others.
The CDC investigators also discussed why communities tended to use so many resources to try to find environmental causes for conditions that appeared to be psychogenic. The problem is that while public health professionals often suspect that an outbreak is psychogenic, they feel they have no choice but to conduct an unreasonably thorough investigation because of intense anxiety in the community. And, of course, it is very difficult, if not impossible, to definitively prove that a mysterious toxic exposure has not simply escaped detection. The CDC investigators noted the possibility of a negative community reaction to an episode labeled as psychogenic, saying, “Physicians and others are understandably reluctant to announce that an outbreak of illness is psychogenic because of the shame and anger that the diagnosis tends to elicit.”14
An Unbearable Sweetness
Outbreaks of epidemic hysteria are not restricted to children and schools. They have been documented in adults too. One systematic review of cases of epidemic hysteria identified seventy outbreaks that occurred between 1973 and 1993 and found that 50 percent of them took place in schools, 40 percent in small towns and factories, and only 10 percent in other settings.15 The outbreaks usually involved at least thirty people, and often hundreds. Most outbreaks lasted less than two weeks, but 20 percent lasted more than a month.
One of the more improbable examples was the case of the “phantom anesthetist of Mattoon.” In 1944, over a period of a few weeks during the climax of World War II, many adult residents of Mattoon, Illinois, became convinced that an “evil genius” was on the loose in their town of fifteen thousand people. This unseen person would open bedroom windows and spray victims with a “sweet-smelling” anesthetic gas that would temporarily paralyze them but, strangely, leave others in the same room unaffected. Citizens banded together to form armed patrols, but the anesthetist was never caught. The local sheriff, fearing that an innocent person might be shot, eventually ordered the posses to disband. As one investigator of this outbreak dryly noted, “The ‘gasser’ hypothesis asserts that the symptoms were produced by a gas which was sprayed on the victims by some ingenious fiend who has been able to elude the police. This explanation…is widely believed in Mattoon at present. The alternative hypothesis is that the symptoms were due to hysteria.”16
Another, more recent case occurred in 1990 among the Triborough Bridge toll employees in New York City. On February 16, workers began to complain of headaches, abdominal discomfort, dizziness, and throat and chest pain. More and more workers came down with the same symptoms over the next several days, with some of the ill workers noting what they described as a “sweetness” in the air. Symptoms were reported when workers were inside or near a toll booth, but they would subside soon after workers left the booths. The outbreak ended on February 22, when some of the workers’ superiors sat with them at the tolls. By that time, thirty-four workers had become ill enough to go to the hospital, and many others shared their symptoms. After spending hundreds of thousands of dollars searching in vain among dozens of potential culprits for a physical cause of the symptoms, it became clear to many that the illness was psychogenic. It forced 44 percent of the female workers to go to the hospital, almost twice the proportion of male workers with debilitating symptoms.
These cases share many characteristics of MPI. The symptoms tend to pop up in and spread through highly connected communities (with high network transitivity). These communities tend to be isolated and stressed. A physical culprit is seldom found. In most cases, the majority of those affected are women. It is not clear why the incidence in women and girls is higher, but it is possible that because women are inclined to discuss their symptoms, more sympathy cases result in other women. The fact that women have a more sensitive sense of smell might also play a role.
For some reason that is not well understood, smells, both real and imagined, are frequent triggers of modern outbreaks of MPI. This may have to do with the well-established connection between olfaction and emotions. Experiments have demonstrated that smell and emotion are both regulated by a part of the brain called the orbitofrontal cortex.17 Experiments have also shown that memories evoked by smell induce stronger emotions than those evoked by verbal descriptions of the same odor.18