The emergence of a viral disease most often results from an imbalance in the interaction between the infectious agent, the host, and the environment. After the viral disease has been introduced into a given territory or population and once the initial transmission chains are established, the disease may spread and even become endemic if control measures are not implemented or are not sufficiently effective. While it is difficult to anticipate the emergence and introduction of a new viral disease, the following three areas of response must be developed to limit its impact: (1) anticipation and preparedness; (2) research; and (3) monitoring and surveillance. Finally, to ensure that the measures taken are appropriate given the available data and acceptable to the public, it is essential to systematically rely on a multidisciplinary approach that must be dynamically reassessed.