Context: Listeriosis is a foodborne infection responsible for severe disease. Surveillance of human listeriosis in France is based on both mandatory reporting of cases and voluntary submission of L. monocytogenes strains to the National Reference Center for Listeria (NRC) since 1999. The exhaustiveness of this reporting estimated by capture-recapture is of at least 87%. A recent and consistent increase of sporadic and cluster-associated systemic listeriosis cases has been reported in Europe since several years (since 2006 in France), but remains poorly understood in the absence of any new environmental risk factor(s). A total of 322 cases have been reported in 2009 in France. Three main clinical forms are identified: septicemia, central nervous system and maternal-fetal infection. They have been characterized only through retrospective studies and pooling of heterogeneous patients. Such studies do not provide an accurate picture of the disease and fail to identify precise biological / genetic risk factors for the disease. Prognostic factors associated with higher risk of death, of severe neurological impairment or of fetal loss also remain to be determined.