There is a strong and consistent association between ED visits for GI illness and facility outbreaks, the majority of which are suspected to be caused by norovirus (4, 5) . The strength of observed associations was similar when using a vomiting, diarrhea or combined GI syndromes; no significant correlations were observed when using the narrow bloody diarrhea syndrome. HEDSS GI syndromes were inversely correlated with illness caused by bacterial enteric pathogens, even when using the bloody diarrhea syndrome to identify more severe illness or controlling for seasonality. The HEDSS system is a critical tool for situational awareness of community gastrointestinal illness, particularly that which is caused by norovirus. Since norovirus is not a reportable condition in Connecticut, this system is used as the primary source of monitoring community GI illness.