Validation of Promising Biomarker Assays to Assess Their Diagnostic Performance Characteristics

Inclusion Criteria: Any non-severely ill subject presenting with acute fever defined as: temperature of more than 38°C at initial evaluation of less than 7 days of symptoms at presentation. Inclusion criteria: * Children 2-17 years of age * Adults 18-65 years of age * Signed written informed consent for study participation. For recruitment purposes, subjects will be classified into two groups, children and adults. For children, age \>2 years is the minimum cut-off, based on the amount of blood volume to be obtained in the study. WHO guidelines for allowable blood volume in 24 hours recommend that no more than 1-5% of total blood volume (75-80 ml/kg for older children) be obtained. Applying the average weight of a 2 year old toddler =12 kg, the allowable blood volume to be drawn in 24 hours at 1-5% of the total blood volume is 9.6 - 48 mL . For minors, caregivers will provide informed consent. Documented assent for children of 12 to 16 years of age will be required for their participation. Exclusion Criteria: * Subjects who are felt to be in critical condition (based on clinician assessment or the presence of any general signs of critical illness as defined by WHO guidelines (for children: extensive vomiting, active seizure or recent history of seizures, altered mentation, inability to feed, or any of the severe IMNCI classifications; for adults: impending airway obstruction, central cyanosis, severe respiratory distress, feeble pulse, active seizure or recent history of seizures, or unconsciousness) because the target population for the study is non-severe febrile subjects. * Subjects can only be enrolled once into the study.