Code-based Syndromic Surveillance for Influenzalike Illness by International Classification of Diseases, Ninth Revision
Figure 4. Percentage of visits for influenza-like illness (ILI) using both the large and small syndrome groups among military outpatient visits nationwide compared with Centers for Disease Control and Prevention (CDC) sentinel clinician reports from October 2001 through December 2004. Data are grouped weekly from Sunday through Saturday. CDC data are only obtained during the influenza season. ESSENCE, Electronic Surveillance System for the Early Notification of Community-based Epidemics.