Hulth and Rydevik BMC Public Health 2011, 11:252 http://www.biomedcentral.com/1471-2458/11/252 C O R R E S P O N D E N C E Anette Hulth* and Gustaf Rydevik Abstract Open Access GET WELL: an automated surveillance system for gaining new epidemiological knowledge Background: The assumption behind the presented work is that the information people search for on the internet reflects the disease status in society. By having access to this source of information, epidemiologists can get a valuable complement to the traditional surveillance and potentially get new and timely epidemiological insights. For this purpose, the Swedish Institute for Infectious Disease Control collaborates with a medical web site in Sweden. Methods: We built an application consisting of two conceptual parts. One part allows for trends, based on user specified requests, to be extracted from anonymous web query data from a Swedish medical web site. The second conceptual part permits tailored analyses of particular diseases, where more complex statistical methods are applied to the data. To evaluate the epidemiological relevance of the output, we compared Google search data and search data from the medical web site. Results: In the paper, we give concrete examples of the output from the web query-based system. We also present results from the comparison between data from the search engine Google and search data from the national medical web site. Conclusions: The application is in regular use at the Swedish Institute for Infectious Disease Control. A system based on web queries is flexible in that it can be adapted to any disease; we get information on other individuals than those who seek medical care; and the data do not suffer from reporting delays. Although Google data are based on a substantially larger search volume, search patterns obtained from the medical web site may still convey more information from an epidemiological perspective. Furthermore we can see advantages with having full access to the raw data. Background During the last couple of years, logs of queries sub- mitted to web-based search engines have received atten- tion as potential sources for infectious disease surveillance. There are several advantages with using web queries for epidemiological analyses: We can get information on groups of individuals other than those who see a doctor. The data are nearly real-time. A system based on web queries can easily be adapted to various diseases. * Correspondence: anette.hulth@smi.se Swedish Institute for Infectious Disease Control, SE-171 82 Solna, Sweden The data reflect a point in time close to onset (provided that the person looking for information is actually ill). This paper describes a fully implemented surveillance system that can generate epidemiological trends from anonymous web query logs. We have named the appli- cation GET WELL: Generating Epidemiological Trends from WEb Logs, Like. The system was developed at the Swedish Institute for Infectious Disease Control (SMI). The purpose of GET WELL is to provide a complement to the daily surveillance performed by the epidemiolo- gists at the institute. For example, the generated output can give additional information about a disease, by con- firming or contradicting signals of an outbreak from other surveillance systems. In this paper, we present examples of output from GET WELL. We also present a © 2011 Hulth and Rydevik; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.