12 Human Health and Global Environmental Change
Syndromic surveillance enhancing public health responsiveness to global change - a European perspective A. Ziemann, T. Krafft, N. Rosenkötter, L.G.C. Riesgo, G. Vergeiner, M. Fischer, F. Lippert, A. Krämer, P. Pinheiro, H. Brand, M. Rosenberg,
Can syndromic surveillance be a valuable tool for enhancing the responsiveness of public health to global change? The verdict on the usefulness of syndromic surveillance is pending. Opinions range between stressing its potentials for a low-cost warning of (unknown) public health threats, such as newly emerging infectious or environmental diseases earlier than by traditional surveillance systems and its limitations due to a lower specificity and a higher number of false alerts compared to disease-specific surveillance. While being an established supplement to traditional disease surveillance methods in the USA and the UK for some years, continental Europe, the European Union, and many other countries around the world continue to discuss whether there is an added value of this approach. During the 2nd European Public Health Conference held in November 2009 in Lodz, Poland a session posed the question: “Syndromic surveillance in Europe – Needed or Needless?” The answers gathered by a half-standardised survey mirrored somehow the inconclusiveness, with at least 15% of public health research and practice representatives attend-
IHDP Update Issue 1, 2011
ing the session answering “not sure”. The respondents also provided clear insights into the reasons why syndromic surveillance is not applied at their services or in their studies. It is not so much the perceived or actual high number of false alerts but rather a lack of experience with or knowledge about syndromic surveillance and the missing link to the part of the health sector that could provide syndromic data (cf. figure 1).
What is the discussion around syndromic surveillance? While being a well-established concept for routine surveillance in some developing countries, the concept of syndromic surveillance attracted new interest in the developed world after the 2001 terrorist attacks. Since then, the approach has been applied and researched mainly in AngloAmerican countries for the purpose of early detection of bioterrorist events. In Europe, facing new health threats from heat waves and emerging infectious diseases, syndromic surveillance systems are now gaining new interest. Syndromic surveillance does not replace but supports existing public health surveillance struc-
tures. Pre-diagnostic, routinely and electronically collected data, often gathered for a different purpose can be automatically analysed. Examples of the types of data that can be used are over-the-counter drug sales, calls to health advice hotlines, emergency department chief complaints, work or school absenteeism information, or internet search behaviour. Syndromic surveillance systems can detect respiratory and gastrointestinal diseases, influenza-like-illness and environmental threats such as heat-related illness. Success seems to be highly dependent on the syndrome that was chosen as proxy for the health threat and on the respective data source. Over the years, different temporal and spatial statistical algorithms have been developed to improve the timeliness of early detection of public health events. Parallel to the improved performance, the discussions about the general usefulness of syndromic surveillance continue: “if syndromic surveillance is the answer – what is the question?” (REINGOLD 2003). Two general limitations are often mentioned in the literature on
Illustrations: Louise Smith
J. Overton on behalf of the SIDARTHa project consortium