For more than a century, the provision of safe drinking water and the prevention of waterborne infectious risks essentially rely on water microbiology. However the water microbiological monitoring provides limited information in case of chlorinated water. As well, neither the water microbiological monitoring nor the reporting of disease case clusters by field actors enables a good coverage of waterborne outbreaks. Meanwhile, syndromic surveillance systems have been built up in connection with the development in the 2000s of databases devoted to health care management. This thesis dissertation shows the relevance of the surveillance of the acute gastroenteritis (AGE) incidence based on prescribed drug reimbursement data from the French social security, for the study and prevention of the waterborne infectious risk of fecal origin. It details the method used for the design of the indicator of AGE incidence, and its application to the retrospective detection of waterborne AGE outbreaks and to the study of the infectious risk due to large distribution units (time series studies). However the potential of a surveillance frame, including syndromic data and various data resources on exposure, exceeds the scope of these two applications. This frame should help identify, characterize and monitor tap water related risk factors in the context of global change. In the other hand, the erosion of the sensitivity of the AGE indicator, which could result from changes in the reimbursement rates of health cares, may challenges the follow-up of the waterborne AGE impact over time.
