[The roles for modeling in epidemiology].

Mathematical modelling in epidemiology was pioneered by D. Bernoulli in 1760 in his work demonstrating the effectiveness of the technique of variolation against smallpox. Mathematical epidemiology concerns presently infectious diseases (such as HIV infection, hepatitis C, Prion diseases, influenza, etc.) as well as non-infectious diseases (e.g. cancer). The roles of modelling in epidemiology are: 1) description of complex data in order to facilitate the dissemination of results; 2) demonstration of general laws governing the dynamics of epidemics; 3) estimation of the values of parameters that cannot be directly measured; 4) prediction of future disease burdens; 5) selection of optimal experimental designs.