The control of the transmissible epidemics of diseases requires fast and effective tools for data acquisition, analysis, and information feedback to the actors of health like to general public. We present a tool for the fast creation of platforms of monitoring on Internet allowing the collection and the analysis in real time of the epidemic data of any origin with the dynamic and interactive cartographic representation. A Web-based Geographic Information System (Web-GIS) has been designed for communicable diseases monitoring. The Web-GIS was coupled to a data warehouse and embedded in an n-tier architecture designed as the Multi-Source Information System. It allows to access views of communicable diseases. Thus it is a useful tool for supporting health care decision-making for communicable diseases.This tool is based on the 20 years experiment of the Network Sentinels, with the daily participation of the general practitioners.