 The investigators hypothesize that acute respiratory infections are the main cause of adult febrile illness in a urban low-income setting and that use of quantitative molecular assays on naso-oropharyngeal samples can improve the diagnosis of pneumonia. The investigators also think that the spectrum of infections is different between children and adults, mainly due to a high HIV prevalence in adults. The investigators also hypothesize that experiencing IAP and or DM is a risk factor for infections in adults. 