Using syndromic surveillance data for identification of hazardous-toxic cases and clusters

The chief function of syndromic surveillance is early recognition of adverse public health events. During 2007, several hazardous-toxic situations were identified when COSD performed daily analysis of emergency department (ED) data. ED encounter data are sent daily from 8 hospitals and include: date of visit, age, zip code, chief complaint (CC), mode of arrival, and disposition. SAS-based algorithms query CCs for key words. Results were reviewed follow-up was conducted as needed. Hazardous-toxic key words include: exposure, chemical, inhalational injury, radiologic, and toxic. Results were reviewed; follow-up included obtaining patient information from the hospital and contacting the COSD's Environmental Health's Hazardous Materials Division (HMD). Several hazardous-toxic situations were identified, including four listed here. 1) A patient presented to the ED for occupational “radiological exposure”. 2) A cluster of cases seen for “exposure” had symptoms of nausea, headache, and dizziness related to inhalation of unknown chemicals. 3) Three cases seen for ‘inhalational injury' were exposed to ventilated noxious fumes at work. 4) Nine patients were seen for “chemical exposure” related to a formaldehyde release at a pet hospital. HMD conducted followed up on all of these events, including 3 site visits. Several hazardous-toxic events of public health interest were identified using syndromic surveillance data. COSD was able to collaborate with hospitals and HMD. This epidemiological tool helped facilitate one of public health's core functions – to identify and respond to adverse health events.