[Risk of importation of tropical diseases in metropolitan France: dectection, alert, response].

The French public health institute is responsible for promoting and coordinating threats the detection and assessment of health risks, and for suggesting possible responses. Transmissible diseases affecting both human and animal health are the focus of surveillance networks. Early detection of potential infectious threats is based on the screening of "alert signals" identified through routine surveillance networks and other systems. The quality and accuracy of these signals is first verified, before assessing, through a multidisciplinary approach, the risk of introduction and dissemination. This article examines specific cases illustrating the process of detection, risk analysis and response, with respect to infectious threats that are endemic in tropical regions and have the potential to be imported into metropolitan France. For both novel pathogens and exotic diseases--which, not being endemic in France, are less well known--the analysis and response process must regularly be adapted to the latest epidemiological, clinical and biological findings, taking interactions between the pathogen, host, and environment into consideration. The need to improve reaction times and risk assessment is also discussed.