Medical Inquiry

Experts say mass hysteria typically begins when one or several individuals in a group become ill under stress. Others manifest similar symptoms, which typically include nausea, muscle weakness and headaches.

The Ministry of Health investigators found that the patients fell ill in the same factory but at different workshops and at different times, reporting smelling of different odors. "They did not manifest typical or regular symptoms, or uniform organic damages.  Tests did not produce accurate positive results. Auxiliary test results offered no clinical reference.

Their investigation report also mentioned that inspection tests of air quality at the Jilin Chemical showed that harmful chemicals are within the permitted level and that the patients' symptoms are not typical of acute chemical poisoning.

Suspicions of hysteria emerged among health investigators after authorities officially reported that none of Connell's employees said they were poisoned, and the number of Jilin Chemical Fibre workers reporting sicknesses continued rising even after Connell halted production.

Neither environmental protection nor work safety authorities detected any irregularities among workers and operations at the Connell plant.

Symptoms of hysteria should be behavioral. However, health records and medical examination results from several affected workers revealed organic abnormalities, including temporary excessive levels of carbonyl hemoglobin, which is a typical indicator of monoxide poisoning and sometimes can be detected in heavy smokers too.

Some suggested that Jilin Chemical Fibre was a more likely source of any toxic discharges. But workers at Jilin Chemical Fibre argued its emissions, which include sulfureted hydrogen and carbon bisulfide, had been normal.

Cases of psychogenic illness have been reported in the past in China and around the world. To determine whether the Jilin incident definitely fits the pattern, specialists say they need more testing and time to exclude all other possible explanations. But the size and scope of the latest event could make it one of the largest cases ever in China.

In June 2005, a six-year-old student died and more than 100 students showed "irregular reactions" during an inoculation of 2,500 primary and middle school students in Dazhuang Village, Si County, in Anhui Province, in a mass psychogenic illness diagnosed by the Health of Ministry investigator.