Enhanced surveillance of shellfish mortality to improve early detection and investigation of outbreaks of exotic or emerging infectious diseases: An example of a mass mortality outbreak of mussels, France 2014

• The relevance and feasibility of enhanced passive surveillance of mussel mortality were assessed.
• This flexible method was based on regular telephone interviews of a key informant from a farming community.
• This method improved the early detection and description of outbreaks of mussel mortality.
• This method was valuable for generating hypotheses for the future investigation of outbreaks.
• This method requires out-reach to the community-based information network of the mussel farmers.

This paper explores the relevance and feasibility of enhanced surveillance of mussel-related mortality based on regular telephone interviews of a key informant in a farming community. Based on qualitative analyses of data collected through semi-structured interviews, this method of participatory disease surveillance enabled the retrieval of high quality data during an outbreak of mussel mortality which occurred in Pertuis Charentais, France, in 2014.The findings illustrated that such an enhanced surveillance approach compared with the institutional shellfish health surveillance system could improve the early detection of outbreaks of mussel mortality by one week. This approach enabled a detailed description of the outbreak, showing higher incidence proportion in the Northern water bodies. It also captured relevant data for hypothesis generation for further outbreak investigations, integrating a global view of the health and disturbance of the coastal marine ecosystem. However, to be effective and sustainable, this flexible approach requires a pre-existing knowledge of the structure of the information network of the farmers’ community. Such a community-based enhanced surveillance could increase the reactivity of the entire system to enable the earliest possible and most appropriate interventions to protect shellfish populations against exotic or emerging infectious diseases. This would also help to improve the vigilance of mussel farmers and foster their commitment, which is an essential element for sustainable shellfish health surveillance.