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Use of entomology surveillance data for modeling Culicoides abundance in mainland France

Villard P., Munoz F., Balenghien T., Lancelot R., Hénaux V.. 2018. In : Abstract Book of the 15th International Symposium of Veterinary Epidemiology and Economics (ISVEE 15). Chiang Mai : ISVEE, p. 34-34. International Symposium of Veterinary Epidemiology and Economics (ISVEE 15). 15, 2018-11-12/2018-11-16, Chiang Mai (Thaïlande).

Objective: In France, Culicoides surveillance was implemented in 2002 in specific areas (Corsica and Mediterranean coastal mainland) and in the whole metropolitan France during 2009-2012 to monitor vectors activity during bluetongue epizootics. The national-scale surveillance was implemented again following the re-emergence in 2015. The purpose of this study was to model the abundance of Culicoides using surveillance data. Materials and methods: Since 2016, the Culicoides surveillance network operates in 24 eco-climatic zones, with one night trapping per week in one site per eco-climatic zone. Eco-climatic zones were delineated by analyzing the catch data collected in France during 2009-2011, and are homogenous in terms of Culicoides abundance, diversity and phenology (start and end of activity period). Minimum and maximum temperature data at each trap location were obtained from Météo France, the French national meteorological service. We applied a specific count model for every eco-climatic zone using a spline transformation of the week number, the minimum and maximum temperature as fixed effects, and the catch site and the year of trapping as random effects. Model fit was evaluated by root mean standard error and mean absolute error. Result(s): Overall, the model provided a good fit to the data for the 24 eco-climatic zones. They showed that the annual distribution of Culicoides varied in terms of abundance, duration, onset and end of activity period, and shape (one or two peaks, with or without plateaus). Conclusion: Although data were collected for surveillance purposes, our modelling approach integrating minimum and maximum temperatures, which are known to be major drivers for Culicoides activity, allowed us to predict annual variations in abundance in each zone. Our results may be used to predict at-risk period within each eco-climatic zone and to model bluetongue dynamics and spread in mainland France. This information is essential to define risk-based surveillance programs.

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