A Cohort Study to Determine the Incidence of Dengue Fever and to Build Capacity for Dengue Vaccine Trials in Dengue-endemic Regions of South Asia

Inclusion Criteria: * Subject and/or subject's parent(s)/legally acceptable representative(s) (LAR\[s\]) who, in the opinion of the investigator, can and will comply with the requirements of the protocol. (e.g., willingness to go to the hospital/clinic for visit\[s\] in case of AFI, able to observe the signs of dengue and to understand how to take and report body temperature, etc.). * Signed/thumb-printed (and video recorded if required by law) informed consent (and assent if applicable) must be obtained from the subject/subject's parent(s)/LAR(s) at the hospital/clinic or during a home visit. If the subject/subject's parent(s)/LAR(s) are illiterate, the informed consent form (ICF) (or informed assent form \[IAF\] when applicable) will be countersigned by an impartial witness. * Subject is part of a household with at least one child (aged less than 18 years) and in which informed consent (and assent if applicable) to study participation was obtained from at least one adult and one child. * Male or female aged between and including 6 months and 50 years at the time of enrolment. * Subject who plans, at the time of enrolment, to remain at same residence/study area during the two-year study period. Exclusion Criteria: * Child in care. * Participation (current or planned) in another epidemiological study or in a clinical trial that would conflict with the current study, based on investigator's judgement. * Terminal illness based on investigator's judgement. * Mental incapacity…