Vector-borne diseases spread and control: The case of Chikungunya in French overseas territories and consequences for dissemination in mainland territory

Dengue, chikungunya and Zika viruses have expanded their geographic range during recent decades and are now considered emerging threats in temperate areas. In particular autochthonous transmissions of chikungunya virus (CHIKV) have regularly been observed in Europe since 2010. The increase in international travel and trade appear to be major factors, encouraging both a circulation of these viruses on a global scale and the dispersion of one of their main vectors. This trend is likely to increase significantly in the future and improved preparedness and response strategies are essential to manage these emerging risks. It is therefore important to understand the factors driving virus dynamics in tropical areas to identify way to improve its control in this context, as well as being prepared to control efficiently multiple importations inside temperate areas. To this extent, we have analyzed the spatio-temporal dynamics of Chikungunya virus in a French overseas territory during the 2014 outbreak. Through a combination of mathematical modeling and digital epidemiology analysis, we characterized the role of human behavior on viral propagation. Second, we developed a mathematical model for CHIKV transmission in mainland France. We estimated key model parameters of CHIKV transmission and vector control effectiveness, using data from the two main CHIKV transmission events which have already occurred. The model was then used to forecast the magnitude of outbreaks as a function of the delay in implementing control measures, and from the moment of virus introduction during the mosquito vector season. This work will help provide stakeholders in public health with a greater understanding of the dynamics of CHIKV transmission, and with evidence for the implementation of sustainable surveillance systems.