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An outbreak of itching in an elementary school--a case of mass psychogenic response.

On March 15, 2006, during the week of Maryland School Assessment (MSA) testing, several fifth-grade students housed in a portable classroom began complaining of skin irritation and severe itching. Students seen in the health room reported pruritus on exposed areas of skin. Evaluation by school nurses identified erythema in areas vigorously rubbed or scratched by students and no other skin lesions or exanthem. No fever or other signs of systemic illness were present. Erythema often resolved while students waited in the health room.

By the end of the school day on March 15, 18 students, including 12 out of 31 students from the initial portable classroom, visited the health room and were sent home with instructions to see their primary care physician if symptoms persisted. Classes were relocated from the portable classroom although initial environmental investigations revealed no obvious etiology for the widespread itching. Classrooms were cleaned thoroughly. Air filters were removed for evaluation and air monitoring was established.

Over the following days, health room visits for complaints of itching continued and spread to additional classrooms and grades throughout the main school building (Figure 1). On the morning of March 17, members of the media were conducting interviews regarding the outbreak of itching with students and parents on their way to school. By that afternoon, camera crews and a news helicopter were present. That day, the school health room had 35 visits for pruritus.

Medical evaluations by primary care physicians documented non-contagious rashes of unknown etiology or that erythema resolved prior to being seen. Environmental investigation included over 70 hours of air sampling in each of the 2 locations, testing air cleanliness (particulate and total volatile organic compounds), building pollutants (carbon monoxide, ozone, and radon), and comfort and ventilation parameters (temperature, humidity, and carbon dioxide as an indicator of ventilation). Air sampling began in the initial portable classroom at 7:30 AM, March 17, and in the main school building at 1:00 PM, March 20. The only finding of interest from the environmental inspection was low relative humidity in the air in both the portable classroom and the main school building. Relative humidity should be maintained between 20% and 60% for the comfort of occupants. During the testing periods, the portable classroom and main school building experienced ranges in humidity from 15% to 24% and 12% to 20%, respectively. Average temperatures were 69[degrees]F and 73[degrees]F, respectively.


On March 20, in the absence of infectious, medical, or environmental etiology for the pruritus, a meeting was held with school staff to present findings. Staff were reassured that no serious problems existed and dry skin associated with low humidity was postulated as a possible trigger for the events. They were advised to be calm and return focus in the classroom to schoolwork. Portable classrooms were reopened, and students seen for itchy rash in the health room in the absence of any other symptoms were treated with cal amine lotion, reassured, and returned to class. Parental, media, and community concerns regarding the safety of the school were addressed by school administrators and the health department thereby alleviating anxiety over the outbreak. By March 21, the last case of itching was seen in the health room and the school returned to normal operations.


During the outbreak, there were 93 visits to the health room for itching, comprising 58 students and 3 staff. Of the total student body, 9% visited the health room. Girls were affected twice as much as boys (12.7%, 6.0%, respectively). The majority of students seen early in the outbreak were from the fifth grade, and itching spread to younger students as time passed (Figure 2). The final attack rate of itching by school grade was as follows: 25% of the fifth grade, 16% of the fourth, 8% of the third, 5% of the first, and none of the second grade. MSA testing was suspended for affected classes and was moved to make up periods.

As multiple medical evaluations discovered no infectious or medical etiology and extensive environmental investigations identified only dry air, the initial pruritic rash was believed to be related to dry skin exacerbated by low humidity within the portable classroom. Propagation of itching to the rest of the school over subsequent days appears to have been by mass psychogenic response (MPR).


MPR, also referred to as epidemic hysteria, mass hysteria, or mass psychological illness, has been identified for over 600 years. MPR is a syndrome comprising a collection of symptoms, which are consistent with organic illness, but lack an identifiable cause, and which rapidly spread through socially connected groups due to psychogenic factors. (1) Symptoms are often described following a perceived or suspected exposure, such as a strange odor, and can be difficult to differentiate from illness stemming from infectious or environmental etiologies. Predominant symptoms found in case reports of MPR include headache, light-headedness, abdominal pain, cough, hyperventilation, irritated eyes, rash, itching, and weakness, with the majority of reported outbreaks occurring in school settings. (1-3) Episodes of MPR may be more common than previously thought. Risk may be increasing in the present-day setting of increased anxiety and vulnerability from perceived threats of biological warfare and terrorism. (2-4) Spread of symptoms through MPR results in great anxiety, social disruption, unnecessary medical interventions, and large resource expenditures. Early investigation, identification, and management may prevent the disruptive effects on individuals and communities. (5)

Although MPR is often considered a diagnosis of exclusion, characteristic features have been identified that aid in identification of MPR. MPR symptoms are often inconsistent with a specific biologic cause. They are often benign, transient, and associated with minimal objective physical or laboratory changes. Those affected experience rapid onset and resolution of symptoms. Groups subject to increased stress or anxiety are at increased risk. Symptoms spread via "line of sight," with people becoming ill after seeing or hearing of another's illness. Severity of symptoms often increases when a person is around other symptomatic individuals or those with more severe symptoms. Symptoms spread from older or higher status individuals to younger or those of lesser status. Symptoms may be clustered in time and place and affect groups with similar beliefs concerning the perceived or suspected exposure. There is a preponderance of symptoms in women or girls and adolescents or preadolescents. Relapse often occurs upon return to the initial site of the outbreak. Finally, symptoms commonly escalate with intense media attention or large-scale emergency or medical response. (1,3-8)

In the presence of even a minor environmental trigger and also in more serious events, MPR can complicate response by overloading medical and public health systems, exaggerating the scope and severity of an event and adding to social disruption. Management of MPR outbreaks should aim to restore normal functioning as soon as possible. Interventions thought to be effective include rapid and thorough investigation to rule out communicable or environmental problems; alleviation of anxiety; moderation of media, emergency, and medical response, such as parking emergency vehicles out of sight; separation of affected individuals from unaffected individuals to break line of sight transmission; school or work closure while environmental evaluations are conducted; early dismissal of classes and avoidance of large assemblies within affected schools; and, some suggest, prompt identification and labeling of an episode as a MPR. (3,4,9,10)

This outbreak of pruritus highlights multiple characteristics of MPR: the symptoms were benign and transient; environmental and medical evaluations did not reveal a likely etiology; the students were under psychological stress due to standardized testing; there was line of sight transmission; although the students reported severe itching, the only visible sign was erythema consistent with scratching; the number of students with itching escalated with increasing media coverage; females were affected more than males; itching spread from the fifth graders to the younger students; symptoms began rapidly, spread explosively, and, after reassurance and return to routine, rapidly abated.

Specific measures implemented at the school to control the outbreak included:

* School staff, media, and parents were informed of the findings and urged to reduce attention given to symptoms and return the focus to educational activities. The roles of anxiety and low humidity were discussed.

* In health rooms, students were asked to stop scratching and were observed. In all cases, the rash/erythema disappeared in minutes.

* Instead of sending students home and advising medical evaluation, children with complaints related to the outbreak were checked for objective signs of illness like fever or sore throat. In the absence of objective signs, they were reassured, calamine lotion was applied to affected areas, and they were returned to class. Parents were called as a courtesy, but medical attention was left to their discretion.

* Steps were taken to increase humidity levels in the affected rooms.


While biological and environmental causes must always be considered and evaluated, maintaining a suspicion for MPR in school settings may prevent unnecessary social disruption, anxiety, resource expenditure, and invasive medical interventions. Measures such as those taken by the school and health personnel in this outbreak may be helpful in similar situations.


(1.) Boss LP. Epidemic hysteria: a review of the published literature. Epidemiol Rev. 1997; 19(2):233-243.

(2.) Pastel RH. Collective behaviors: mass panic and outbreaks of multiple unexplained symptoms. Mil Med. 2001; 166 (12 suppl) :44-46.

(3.) Jones TF, Craig AS, Hoy D, et al. Mass psychogenic illness attributed to toxic exposure at a high school. N Engl J Med. 2000; 342 (2): 96-100.

(4.) Bartholomew RE, Wessely S. Protean nature of mass sociogenic illness: from possessed nuns to chemical and biological terrorism tears. Br J Psychiatry. 2002; 180:300-306.

(5.) Krug SE. Mass illness at an intermediate school: toxic fumes or epidemic hysteria? Pediatr Emerg Care. 1992;8(5):280-282.

(6.) Goh KT. Epidemiological enquiries into a school outbreak of an unusual illness. Int J Epidemiol. 1987; 16 (2):265-270.

(7.) Robinson P, Szewczyk M, Haddy L, Jones P, Harvey W. Outbreak of itching and rash. Epidemic hysteria in an elementary school. Arch Intern Med. 1984;144(10):1959-1962.

(8.) Small GW, Borus JF. The influence of newspaper reports on outbreaks of mass hysteria. Psychiatr Q. 1987;58(4):269-278.

(9.) Cole TB, Chorba TL, Horan JM. Patterns of transmission of epidemic hysteria in a school. Epidemiology. 1990;1(3):212-218.

(10.) Small GW, Feinberg DT, Steinberg D, Collins MT. A sudden outbreak of illness suggestive of mass hysteria in schoolchildren. Arch Faro Med. 1994;3(8):711-716.





(a) preventive Medicine Informatics Consultant, (, 5201 Leesburg Pike, Suite 1400, Falls Church, VA 22041-3203.

(b) Assistant Program Manager, School Health Services, (, Anne Arundel County Department of Health, 3 Harry S. Truman Parkway, Annapolis, MD 21401.

(c) Environmental Issues Program Manager, (, Operations Division, 9034 Fort Smallwood Rd, Pasadena, MD 21122.

(d) Deputy Health Officer for Public Health, (, Anne Arundel County Department of Health, 3 Harry S. Truman Parkway, Annapolis, MD 21401.

Address correspondence to: Heather Halvorson, Preventive Medicine Informatics Consultant, (, 5201 Leesburg Pike, Suite 1400, Falls Church, VA 22041-3203.
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Article Details
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Title Annotation:Health Services Application
Author:Halvorson, Heather; Crooks, Janet; LaHart, Daniel A.; Farrell, Katherine P.
Publication:Journal of School Health
Article Type:Case study
Geographic Code:1U5MD
Date:May 1, 2008
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