Mass sociogenic illness by proxy: parentally reported epidemic in an elementary school.

In a cluster of illness reported among students at an elementary school parents mentioned many signs and symptoms including headache, pallor, dark circles under the eyes, nausea, and vomiting--which they attributed to exposure to recurrent leaks of natural gas at the school. It is likely that the parents spread among themselves the notion of toxic exposure at the school. A questionnaire revealed no spatial clustering, but increased reports of symptoms were related to intense media coverage. A thorough environmental and epidemiological investigation was negative, there being no evidence of a continuing gas leak or other potential causes. At a strictly biological level, the complaints in this reported "cluster" apparently represented the sporadic occurrence of common childhood illnesses. The possibility of an epidemic from toxic exposure at the school caused intense parental concern and led to a major public health problem. The established term "mass sociogenic illness" seems inapplicable here because complaints did not come principally from the students and the apparent epidemic illness was not transmitted among them. The term "mass sociogenic illness by proxy" is proposed to describe this incident, in which transmission in one group (the parents) resulted in reports of an epidemic in another group (students).