Funding: ANR, Fondation Raoul Follereau, Fondation SANOFI Espoir. In this new research program, we will conduct for the first time the simultaneous collection of environmental (plants and insects) and human samples in two historically endemic regions located in different climates (equatorial and subtropical in Cameroon and Benin, respectively) and one newly discovered endemic focus close to a dam (in Cameroon). Samples will be analysed for the presence of M.ulcerans, and characterised phylogenetically, to offer better understanding of the circulation of M.ulcerans across ecological niches. Maps of M. ulcerans presence probability, as well as of M. ulcerans exposure risk, will be produced at the regional scale and tentatively expanded at the national scale, to target more efficiently diagnostic and care resources. We will also focus on the role of peri-domestic insects in M.ulcerans transmission. Indeed, two studies of our group suggest that individuals sleeping under mosquito nets are at a lower risk of Buruli ulcer than those who do not. Knowing that in Australia, mosquitoes are considered as potential vectors for M.ulcerans (Lavender C.J. et al., PLoS NTD, 2011), and repellents are recommended for protection against Buruli ulcer, we seek to expand our initial studies by capturing insects around houses and using PCR to search for M.ulcerans DNA in these insects.