Toxic exposure or mass sociogenic illness? The diagnosis can be challenging

February 18, 2012, 12:28 am


Mass Sociogenic Illness Initially Reported as Carbon Monoxide Poisoning. Nordt SP et al. J Emerg Med 2012;42:159-161.


Mass sociogenic illness (MSI) is rare but can occur when large numbers of people gather in school, church, or other settings. The authors of this interesting report point out that MSI can include the following characteristics:

  • cases occur mostly in adolescents and younger populations
  • other individuals from the same setting lack signs and symptoms suggesting exposure or illness
  • there are no laboratory findings supporting a diagnosis of organic illness
  • transmission is by “direct line of sight”
  • onset and resolution are rapid

In the incident described by the authors, 22 persons (age 7 to 50 years) experienced nausea, paresthesia, dyspnea, and syncope while attending church service in a parochial school. Others who attended the mass were unaffected. At the scene, carboxyhemoglobin (COHb) levels measured by a hand-held portable Masimo device were elevated in 6 patients. All these patients had normal COHb on arrival at hospital. Authorities did not find any evidence of carbon monoxide in the environment.

The authors make the following points:

  • MSI can be difficult to diagnosis and differentiate from toxic exposure
  • A diagnosis of MSI should not be made until possible toxicological and organic conditions have been ruled out
  • Non-invasive carbon monoxide testing can cause a high incidence of false-positive results

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