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Attributing foodborne illnesses to food sources is essential to conceive, prioritize, and assess the impact of public health policy measures. The Bayesian microbial subtyping attribution model by Hald et al. is one of the most advanced approaches to attribute sporadic cases; it namely allows taking into account the level of exposure to the sources and the differences between bacterial types and between sources. This step forward requires introducing type and source-dependent parameters, and generates overparameterization, which was addressed in Hald's paper by setting some parameters to constant values. We question the impact of the choices made for the parameterization (parameters set and values used) on model robustness and propose an alternative parameterization for the Hald model. We illustrate this analysis with the 2005 French data set of non-typhi Salmonella. Mullner's modified Hald model and a simple deterministic model were used to compare the results and assess the accuracy of the estimates. Setting the parameters for bacterial types specific to a unique source instead of the most frequent one and using data-based values instead of arbitrary values enhanced the convergence and adequacy of the estimates and led to attribution estimates consistent with the other models' results. The type and source parameters estimates were also coherent with Mullner's model estimates. The model appeared to be highly sensitive to parameterization. The proposed solution based on specific types and data-based values improved the robustness of estimates and enabled the use of this highly valuable tool successfully with the French data set.

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Salmonella are the most common bacterial cause of foodborne infections in France and ubiquitous pathogens present in many animal productions. Assessing the relative contribution of the different food-animal sources to the burden of human cases is a key step towards the conception, prioritization and assessment of efficient control policy measures. For this purpose, we considered a Bayesian microbial subtyping attribution approach based on a previous published model (Hald et al., 2004). It requires quality integrated data on human cases and on the contamination of their food sources, per serotype and microbial subtype, which were retrieved from the French integrated surveillance system for Salmonella. The quality of the data available for such an approach is an issue for many countries in which the surveillance system has not been designed for this purpose. In France, the sources are monitored simultaneously by an active, regulation-based surveillance system that produces representative prevalence data (as ideally required for the approach) and a passive system relying on voluntary laboratories that produces data not meeting the standards set by Hald et al. (2004) but covering a broader range of sources. These data allowed us to study the impact of data quality on the attribution results, globally and focusing on specific features of the data (number of sources and contamination indicator). The microbial subtyping attribution model was run using an adapted parameterization previously proposed (David et al., 2012). A total of 9076 domestic sporadic cases were included in the analyses as well as 9 sources among which 5 were common to the active and the passive datasets. The greatest impact on the attribution results was observed for the number of sources. Thus, especially in the absence of data on imported products, the attribution estimates presented here should be considered with caution. The results were comparable for both types of surveillance, leading to the conclusion that passive data constitute a potential cost-effective complement to active data collection, especially interesting because the former encompass a greater number of sources. The model appeared robust to the type of surveillance, and provided that some methodological aspects of the model can be enhanced, it could also serve as a risk-based guidance tool for active surveillance systems.

Objective: To describe part of the results of the CALIPSO study, i.e. to provide seafood consumption data on high seafood consumers in France and its contribution to n-3 long-chain (LC) PUFA intake. Design and subjects: A total of 1011 individuals aged 18 years and over, who consumed fish and seafood at least twice weekly, were recruited. A consumption survey and a local 'total diet study' were performed to examine seafood consumption, fatty acids composition of seafood and to assess n-3 LC PUFA intake. Setting: The CALIPSO survey was conducted in four French coastal regions (Le Havre, Lorient, La Rochelle and Toulon). Methods: The subjects were questioned about their consumption habits, especially concerning fish and seafood, through a first validated FFQ. A sample of the most consumed seafood products (n 47) was analysed for each region for its fatty acid composition. Fatty acids and especially n-3 LC PUFA intakes in this population were then calculated. Results and conclusions: The average consumption of fresh and frozen fish was found to be 633, 636?5 and 787?8 g/week among men aged 18-64 years, women aged 18-64 years and people over 65 years, respectively. In these population groups, the consumption of crustaceans and molluscs was 270?3, 259?9 and 279?3 g/week, respectively. The results show that, irrespective of the age group and gender, consumption of fish and seafood twice weekly without excluding oily fish allowed people to reach the national and international recommended n-3 LC PUFA intakes and demonstrates the validity of the French recommendations for fish consumption. KeywordsFish Seafood Consumption Fatty acids Omega 3For many years seafood, i.e. fish, molluscs and crustaceans, has often been the focus of attention in nutritional research and recommendations. These products are considered to be an important source of iodine, vitamin D, proteins and fatty acids, especially the n-3 long-chain (LC) PUFA, although only half the French population follows the recommendation of the French National Nutritional-Health Programme to consume fish at least twice a week (1) . The protective role of n-3 PUFA has been demonstrated in primary prevention and, above all, secondary prevention of CVD. n-3 LC PUFA might help to reduce mortality from CVD, though not morbidity (2,3) . n-3 LC PUFA supplements might help to reduce cardiovascular risks by lowering the risk of sudden death of people with a history of cardiovascular problems (4) . Dietary n-3 LC PUFA and n-3 LC PUFA supplements have been demonstrated to be linked with n-3 LC PUFA concentrations in blood, plasma, tissues or human milk, being responsible for beneficial effects on visual and mental health and neurodevelopment (5,6) .Nevertheless, at present, the respective mechanism of action of each of EPA and DHA is debatable. As described in the Symposium 'n-3 fatty acids: recommendations for therapeutics and prevention' convened by the Institute for Human Nutrition of Columbia University on 21 May 2005 (7) , confusion exists about the recommendations ...