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Syndromic Surveillance of Norovirus Using Sales of Non-Prescription Medications for Gastroenteritis


Syndromic surveillance using over the counter (OTC) sales has been shown to provide earlier signals of diarrheal and respiratory disease outbreaks than hospital diagnoses. Under normal circumstances, sales patterns of OTC sales related to gastrointestinal illness (GI) are high in the winter and low in the summer. The Canadian laboratory-based surveillance system that provides weekly counts of reportable bacterial, parasitic and viral isolates by province, has shown that bacterial and parasitic infections tend to be higher in summer and early fall, whereas viral infections (particularly Norovirus and Rotavirus) appear to peak in winter and spring. This suggests that the OTC sales reflect underlying community viral infections rather than bacterial or parasitic infections. If OTC sales are to be considered for use in syndromic surveillance of community GI, the nature of this relationship needs to be clarified. The main objective of this study was to compare temporal distributions of GI-related OTC sales to laboratory-isolate patterns of bacterial, parasitic and viral cases of human GI infections.



To assess if OTC sales of GI related medications are associated with temporal trends of reportable community viral, bacterial and parasitic infections.

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