The IDIS study aims to develop a new rapid diagnostic test for invasive salmonellosis using samples (blood, urine) collected from patients with fever and healthy controls at the Institute of Tropical Medicine (ITM) and collaborating centers. The samples are collected after informed consent and/or assent is given by the participant and are stored in a -80 ⁰C freezer after processing (centrifugation and/or aliquoting). Basic information regarding the patient and the samples are coded and stored in a protected Microsoft Access database. The samples will be shipped to Belgium for proteomic analysis. Identification of Salmonella specific proteins in the samples will hopefully support the development of a rapid diagnostic test. Once this test has been developed, the samples will also be used for validation and evaluation of this test.