Listeriosis is a foodborne infection responsible for severe disease. Three main forms are described: septicaemia, central nervous system infections and maternal-fetal infections. Available data on the disease, are mostly retrospective and do not provide an accurate picture of the clinical / biological / genetic risk factors for the disease, nor identify any element to determine which patients are at higher risk of death, severe neurological impairment or fetal loss.

The primary purpose of the study is to identify clinical, biological and genetic risk factors for systemic listeriosis and the determinants of listeriosis-associated mortality in the setting of a large prospective nation-wide study.

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.

Main purpose:

- to study clinical, biological and genetic risk factors for systemic listeriosis and identify determinants of listeriosis-associated mortality in the setting of a large prospective nation-wide study

Secondary purposes:

• to determine the clinical/biological and radiological presentation of listeriosis
• to describe and further study current therapeutic practices in the 3 forms of the disease (namely, septicaemic, neurologic and maternal-fetal)
• to identify inherited risk factors for listeriosis

Ancillary studies:

- to evaluate serologic/PCR diagnostic tools

Study design:

National prospective multicenter study with nested case control study. Clinical, biological and radiological data are collected. Additionally a questionnaire focusing on dietary habits is proposed. A bank of biological samples is performed. For each patient, 25ml of heparinized blood / and 2ml of serum are collected per patient

Inclusion Criteria:

Case:

• Patient with culture-proven listeriosis (blood, CSF, fetal/placental sample, other…).

Control:

• Patient above the age of 18 years with medical background and clinical features compatible with one of the 3 forms of systemic listeriosis: febrile pregnant women (temp > 38°C), febrile patient with co-morbidity for septicaemic listeriosis, and any febrile symptom leading to empiric amoxicillin prescription.
• For feasibility reasons, controls are included in Paris (France) emergency wards.

Exclusion Criteria:

Case:

• Patient who would refuse to sign informed consent agreement

Control:

• Patient who would refuse to sign informed consent agreement, or whose samples would evidence L. monocytogenes

Case: patient with culture-proven listeriosis (blood CSF, fetal/placental sample, other…).

Controls: patient above the age of 18 years with medical background and clinical features compatible with one of the 3 forms of systemic listeriosis: febrile pregnant women (temp > 38°C), febrile patient with co-morbidity for septicaemic listeriosis, and any febrile symptom leading to empiric amoxicillin prescription.