Vomiting and diarrhea were each highly correlated with the combined GI syndrome (r 00.99, p B0.0001; r 00.93, p B0.001, respectively), although vomiting has a greater magnitude than diarrhea. ED GI visits were correlated with GI hospital admissions (r 00.73, p B0.0001). Similar results were also seen when comparing HEDSS GI data to the number of total reported outbreaks (r00.76, pB0.0001) and facility outbreaks (r00.71, p B0.0001) but not community outbreaks alone (r 0 0.09, p00.23). The combined GI syndrome was inversely correlated with laboratory confirmed cases of Giardia (r0( 0.18, p 00.02), Campylobacter (r 0(0.45, p B0.0001), STEC (r0(0.32, p B0.0001), Listeria (r0(0.23, p 00.004), Salmonella (r0(0.41, p B0.0001), Shigella (r0(0.19, p 00.01), Vibrio (r 0(0.36, p B0.0001). No significant positive correlations were detected when controlling for seasonality or using a narrower syndrome definition. There was no significant geographic variation in GI illness by region. Children younger than 5 years had a proportion of ED visits for GI illness that was consistently higher than all other age groups.