Among the impacts of climate change in West Africa, coastal erosion is the most threatening disaster apart from floods and the increase in temperature. The southern coast of the Dakar region, as part of the most threatened coastal zones in West Africa, records the most current coastal damages in Dakar due to its coastline dynamics and low-lying area. This study was conducted in three littoral cells (Mbao, Bargny and Toubab Dialaw) and aims to investigate if there is a relationship between the coastline dynamic, topographic and slope and the contribution of the geomorphology along the southern coast of Dakar. It helps to understand better the role which plays the topography, Slope and geomorphology in coastal dynamics using remote sensing, cartographic tools and statistical methods. The Modified Normalized Different Water index (MNDWI) was employed to delineate the coastlines before computing the dynamic rate of the coastline using the Digital Shoreline Analysis System (DSAS) software. After that, Topography and Slope were determined using Digital Elevation Model (DEM). Then, the correlation between the coastline dynamic, topography and slope was analyzed through the coefficient of correlation and multiple linear regression model. High dynamic rates were noted in the littoral cells, where the topography and slope are low. In Mbao, there is a significant relationship between the coastline dynamic, topography and slope with a coefficient of correlation of about 0.63. In Bargny, the relationship is also significant, with a coefficient of 0.87. The relationship is not significant in Toubab Dialaw, where topography and Slope are high, with a coefficient of 0.15. We conclude that topography, slope and soil properties play an important role in the study area.

Dengue virus (DENV) was detected in Senegal in 1979 for the first time. Since 2017, unprecedented frequent occurrence of DENV outbreaks was noticed yearly. In this context, epidemiological and molecular evolution data are paramount to decipher virus diffusion route. In the current study, a dengue outbreak occurred in Senegal in 2018 in the context of the largest religious gathering with 263 confirmed DENV cases out of 832 collected samples, including 25 life-threatening cases and 2 deaths. It was characterized by a co-circulation of dengue serotypes 1 and 3. Phylogenetic analysis based on the E gene revealed that the main detected serotype in Touba city was DENV-3 and belonged to Genotype III. Bayesian phylogeographic analysis was performed and suggested one viral introduction around 2017.07 (95 % HPD = 2016.61 – 2017.57) followed by cryptic circulation before identification of the first case on 01 October 2018. DENV-3 strains are phylogenetically related, with strong phylogenetic links between strains retrieved from Burkina Faso and West African countries. These phylogenetic data substantiate epidemiological data of the DENV-3 origin and spread between African countries and subsequent diffusion after religious mass events. The study also highlighted the usefulness of the Mobile Laboratory during outbreak response allowing rapid diagnosis resulting in improved patient management.