Résumé
Audio-visual presentation: Molecular epidemiology -- Identification of the relevant units of analysis of the pathogens involved in transmissible diseases -- Species, subspecies, strains, clones and genes of interest -- Progression of molecular technology -- Infectious diseases are a major concern of public health managers -- Evolutionary concepts enrich the discipline and should be considered an integral part of it -- Use of transmissible diseases as models -- Molecular epidemiology gives evolutionary studies a practical goal.