Hospital admissions syndromic surveillance--Connecticut, September 200-November 2003.

On September 11, 2001, the Connecticut Department of Public Health (CDPH) initiated daily, statewide syndromic surveillance based on unscheduled hospital admissions (HASS). The system's objectives were to monitor for outbreaks caused by Category A biologic agents and evaluate limits in space and time of identified outbreaks. Thirty-two acute-care hospitals were required to report their previous day's unscheduled admissions for 11 syndromes (pneumonia, hemoptysis, respiratory distress, acute neurologic illness, nontraumatic paralysis, sepsis and nontraumatic shock, fever with rash, fever of unknown cause, acute gastrointestinal illness, and possible cutaneous anthrax, and suspected illness clusters). Admissions for pneumonia, gastrointestinal illness, and sepsis were reported most frequently; admissions for fever with rash, possible cutaneous anthrax, and hemoptysis were rare. A method for determining the difference between random and systemic variation was used to identify differences of >/=3 standard deviations for each syndrome from a 6-month moving average. HASS was adapted to meet changing surveillance needs (e.g., surveillance for anthrax, smallpox, and severe acute respiratory syndrome). HASS was sensitive enough to reflect annual increases in hospital-admission rates for pneumonia during the influenza season and to confirm an outbreak of gastrointestinal illness. Follow-up of HASS neurologic-admissions reports has led to diagnosis of West Nile virus encephalitis cases. Report validation, syndrome-criteria standardization among hospitals, and expanded use of outbreak-detection algorithms will enhance the system's usefulness.