<qa>  What is the challenge of few point-of-care tests available for clinicians to identify theThese fevers have the challenge of few point-of-care tests POCT available for the clinicians to identify the etiology of fever and guide treatment in resource-limited countries. As a consequence, over-prescription of antibiotics has increased. In order to improve patient outcomes while supporting judicious use of antimicrobials, there is an urgent need to change the management of febrile patients in low-income countries. This can only be achieved by providing evidence-based clinical guidelines for the management of these acute febrile patients. To develop such guidelines, epidemiological data on etiologies of undifferentiated fever need to be generated. The investigators will evaluate pathogen infection such as dengue, chikungunya and others in 640 patients 2 years old with acute undifferentiated fever. To evaluate the existence of aspecific and subclinical infections and co-infections, the investigators will also test a subsample of 200 patients with ARI, UTI, diarrheal fever and malaria. The investigators expect to have as main results: proportions of each syndrome among fever patients, key pathogens associated with undifferentiated fever and their clinical presentation and demographic characteristics. 