Listeria monocytogenes is a food-borne bacterial contaminant causing a dangerous zoonosis, listeriosis. The virulence mechanisms of this pathogen have been extensively studied, but its asymptomatic carriage in the host is poorly understood. We have discovered a phase of intracellular persistence of Listeria that could explain this portage. This phase is accompanied by a phenotypic switch of Listeria, which enters a state of dormancy in a vacuolar niche. The objectives of the PERMALI project are to develop tools and methods for the detection of persistent intracellular Listeria, and to use them on ex vivo models of listeriosis and clinical (human/animal) samples. The results will allow a better knowledge of the adaptive strategies developed by L. monocytogenes to nest, undetectably, in hosts. They will generate diagnostic and risk management methods to better track Listeria.