Introduction: Recent terrorist activity has highlighted the need to improve surveillance systems for the early detection of chemical or biologic attacks. A new national surveillance system in the United Kingdom (UK) examines symptoms reported to NHS Direct, a telephone health advice service.
Objectives: The aim of the surveillance system is to identify an increase in symptoms indicative of early stages of illness caused either by a deliberate release of a biologic or chemical agent or by common infections.
Methods: Data relating to 10 key syndromes (primarily respiratory and gastrointestinal) are received electronically from 23 call centers covering England and Wales. Data are analyzed daily and statistically significant excesses, termed exceedances, in calls are automatically highlighted and assessed by a multidisciplinary team.
Results: During December 2001-February 2003, a total of 1,811 exceedances occurred, of which 126 required further investigation and 16 resulted in alerts to local or national health-protection teams. Examples of these investigations are described.
Conclusion: Surveillance of call-center data has detected substantial levels of specific syndromes at both national and regional levels. Although no deliberate release of a biologic or chemical agent has been detected thus far by this or any other surveillance system in the UK, the NHS Direct surveillance system continues to be refined.