The Mapplot screen is an interface to ArcIMS, an Internetenabled GIS product developed by Environmental Systems Research Institute, Inc. Mapplot colors zip code regions to indicate the proportion of patients presenting with a particular syndrome. The GIS server also can overlay state boundaries, county boundaries, water bodies, hospital locations, landmarks, streets, and highways on the public health data as shown in Figure 5 . Similar to Epiplot, Mapplot also can display case details for a user-selected zip code.