A conceptual framework for risk stratification to inform the design of risk-based surveillance aimed at early detection of exotic or emerging diseases [P125]

Purpose: The objective is to present a conceptual framework to inform the design of risk-based surveillance aimed at the early detection of exotic or emerging disease. Commonly, free countries consider border areas with infected countries to have the highest probability of exposure. This approach is usually reactive and often does not take into account the epidemiology of an infectious disease, where as a result of trade, hunting or other human behaviours, high risk areas may not lie along these border regions. This means the benefits of a risk-based surveillance approach are not applied effectively. While appropriate tools for estimating this probability of exposure are available, there is a lack of standardization across diseases and countries, and therefore disagreement with respect to the validity of information generated. Methods: We describe and compare the epidemiological tools that are currently available for performing estimation of the spatial and temporal variation in the probability of exposure expanding on recently published systematic review of surveillance systems (Rodriguez-Prieto et al, 2014), classifying them according to data needs and type of analysis (i.e. quantitative, qualitative or semi-quantitative). Advantages and disadvantages of the tools are discussed, and recommendations made for optimum sets of tools will be tested for different types of infectious diseases. Results: Based on the OIE risk assessment framework, we present tools to enable the identification of the threat, to assess the entry through the identification of transmission pathways for the introduction, and to assess the risk of exposure to the threat. Many of the tools presented are based on spatial analysis and have been mainly applied to vector-borne diseases. Conclusions: Not all subpopulations are at equal risk of infection. There are several ways of considering factors to benefit from a risk-based approach to surveillance at each step in the design process. Relevance: The conceptual framework enhances the setting of guidelines for early detection of emerging diseases through the application to a variety of disease models, data needs and technical requirements. (Texte integral)