Inserm has developed, since 1984, an information system based on a computer network of physicians
in France. It allows for constitution of large databases on diseases, with individual description of cases,
and to explore some aspects of the mathematical theory of communicable diseases. We developed userfriendly
interfaces for remote data entry and GIS tools providing real-time atlas of the epidemiologic
situation in any location. The continuous and ongoing surveillance network is constituted of about 1200
sentinel voluntary and unpaid investigators.We studied their motivation, reasons for either withdrawal or
compliance using survival analyses.We implemented early warning systems for outbreak detection and for
time–space forecasting.We conducted epidemiological surveys for investigating outbreaks. Large available
time and space series allowed us to calibrate and explore synchronism of influenza epidemics, to test the
assumption of panmixing in susceptibles-infectious-removed type models and to study the role of closing
school in influenza morbidity and mortality in elderly. More than 250 000 cases of influenza, 150 000 cases
of acute diarrheas, 35 000 patients for whom HIV tests have been prescribed by general practitioners and
25 000 cases of chickenpox have been collected. Detection of regional influenza or acute diarrhea outbreaks
and forecasting of epidemic trends three weeks ahead are currently broadcasted to the French media and
published on Sentiweb© on a weekly basis. Age–cohort–period models assessed field effectiveness of mass
immunization strategies against measles and influenza in the country. Case–control studies with more
than 1200 sets of cases of acute diarrheas and their matched controls showed the role of calicivirus and
rotavirus as probable major causes of gastroenteritis during recurrent widespread outbreaks in winter in
France. An age-specific model for chickenpox showed the probable role of children in disease transmission
to their susceptible parents or grandparents. High level of synchronism between influenza epidemics has
been demonstrated, either at a regional level (in France) or between France and the USA. The designation
of our lab as a WHO collaborating center for electronic disease surveillance stimulates the development
of global monitoring of diseases. We developed operational systems that are now available for the global
monitoring of influenza (FluNet©), and human and animal rabies (RABNET©). Extension of electronic
syndromic surveillance is needed in the world for improving surveillance capacities and real-time response
against emerging diseases.
A Flahault, T Blanchon, Y Dorléans, L Toubiana, JF Vibert and AJ Valleron.
Virtual surveillance of communicable diseases: a 20-year experience in France
