Observational, Prospective Clinical Study to Evaluate Biomarkers as Indicators of Acute Bacterial or Viral Infections

Inclusion Criteria: Patients who are at least one month old and are willing (either the subject or his legal guardian) to sign an informed consent will be eligible for inclusion. For the infectious and non-infectious disease groups, additional inclusion criteria have to be met. These will include: In the Infectious disease group: * Peak fever \>37.5°C (99.5°F) * Clinical suspicion of an acute infectious disease * Symptoms duration ≤ 12 days In the Non-infectious disease control group: \- A non-infectious disease or healthy individuals Exclusion Criteria: Patients who will meet one or more of the following criteria will be excluded from the study: * Evidence of another episode of acute infectious disease in the last two weeks * Diagnosed congenital immune deficiency (CID) * Current treatment with immunosuppressive therapy such as: Active chemotherapy,Post-transplant drugs,High dose steroids (\>1 mg/kg/day prednisone or equivalent). * Active radiotherapy * Immune-modulating/suppressive drugs including monoclonal antibodies, intravenous immunoglobulin (IVIG), cyclosporine, and anti-TNF agents * Current treatment with immune stimulants such as: Interleukin (IL)-2, Granulocyte-Monocytes/Granulocyte colony-stimulating factor (GM/G-CSF),Interferon. * An active hematological malignancy * A diagnosis of myelodysplastic syndrome or myeloproliferative disease * A proven or suspected human immunodeficiency virus (HIV)-1, hepatitis B virus (HBV), or hepatitis C virus (HCV) infection