Sentiweb: French communicable disease surveillance on the world wide web

Sentiweb

Since September 1995 the results of this communicable disease surveillance have been available on a worldwide web site called Sentiweb (http://www.b3e. jussieu.fr/sentiweb). Sentiweb also provides an electronic version of our quarterly paper bulletin Sentinelles, which is currently distributed to 60 000 doctors in France. Sentiweb can also be accessed from several important health related web sites (such as those of the World Health Organisation, Communicable Disease Surveillance Centre, Karolinska Institute, and Centers for Disease Control and Prevention).

Sentiweb provides a way to interactively consult the database. Two kinds of outputs may be requested: time series of incidences of cases and spatial spread of communicable diseases incidences in France. The data can be visualised as maps or curves of incidences within a selected range of time or space (fig 1). Maps may be produced either by means of a classic fill in method based on administrative contours or by a “kriging” fill in method based on iso-incidence contours.3 The system allows a user to request as many as 25 000 different maps and 10 000 graphs of time series. An image is built in 3–15 seconds (excluding transmission time) depending on the complexity of the request. Since its opening, Sentiweb has provided about 9000 maps and time series.

Fig 1

The Sentiweb query interface and a resulting map of influenza in France. Users can browse the database in “real time” and, by choosing the disease (influenza), the year (1995), the time step (50th week), and possibly the type of graphical representation (iso-incidence with contours of regions), can request maps or curves of incidences of communicable diseases in France

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Misuse of information

There is an unavoidable conflict between freedom of access to information and the risk of spurious interpretation of this information, leading in the worst case to a false alert. This is particularly true when searches are made in units of space or time that are too small, leading to analyses that are statistically meaningless. The open philosophy of the Internet brings this problem into the public arena. But do we have any alternative? How do we decide which of the maps or curves are not suitable for public view? Information on small numbers of cases is regularly published on many epidemiological bulletins, and this may be also used spuriously.

We therefore consider that, instead of censoring material, we should train users of the Internet to ask the appropriate questions of such a database. We have posted warnings about inappropriate use of information that appear when any requests for data are made, and users can send email requests for epidemiological help. We also maintain a weekly updated electronic report, written by epidemiologists in simple words, to guide users in their interactive queries on the most recent data. Moreover, the site provides links to other expert information classified by topics (such influenza, diarrhoea) or by organisations (such WHO, CDSC). Thus, users have the opportunity to extend their expertise by comparing our data with those of other sources.

We thank the sentinel general practitioners who collected these data. The Sentinel system was developed at INSERM (national institute of health and medical research) U.444 in collaboration with the Reseau National de Sante Publique (public health network) and the Direction Generale de la Sante (national department of health).