(en) Whether linked to changes in vaccine policy or compliance, climate change or the intensification of population movements (travel, migration), certain infectious diseases whose incidence had fallen sharply at the end of the 20th century have recently resurfaced. Using a few examples, and focusing in particular on certain notifiable diseases, this presentation will review the main clinical features of these diseases, which are or could be back, when to think about them, and how to manage and prevent them.