This Study Will Describe the Burden of DENgue Fever Virus (DENV) Illness Among Household Members Aged 6 Months to 50 Years of Selected Communities in Latin America and Southeast Asia

Inclusion Criteria: * Written and signed informed consent (and assent if the subject is below the legal age of consent) obtained from the subject/from subject's parent(s)/LAR(s). For a subject below the legal age of consent is, his/her signature will be obtained on the informed assent form, if applicable. * A male or female between, and including 6 months and 50 years of age at the time of enrolment (Subjects become ineligible on their 51st birthday). * Subject and/or the subject's parent(s)/LAR(s) who the investigator believes can comply with the requirements of the protocol (e.g., willingness to go to the hospital/healthcare centre for visit(s) in case of acute febrile illness, able to observe the signs of dengue and to understand how to take and report body temperature, etc). * Subject who plans, at the time of enrolment, to remain at same residence/study area during the one or two year study period (as applicable). * Household should be reachable by phone (residence phone or mobile phone). Note: Pregnant or lactating female or female planning to become pregnant can be recruited into the study. 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 or severe mental incapacity.