The objective of this observational study of dengue seroprevalence in the metropolitan area of Buenos Aires is to know what percentage of the population has antibodies against dengue in persons 18 years of age or older who are residents of the city of Buenos Aires or its metropolitan area. The main questions to be answered are:

• What is the seroprevalence of antibodies against dengue measured by Immunoglobulin G determination by ELISA
• Characterize the different dengue serotypes in the affected population. Participants will undergo a small blood draw to determine the presence of Immunoglobulin G antibodies against dengue.
• Tests will also be performed to determine infection by flaviviruses other than dengue virus.

A two-stage stratified design will be used. The primary sampling units will be mostly defined as the census sections of the 2010 National Census of Population, Households and Dwellings. It has 5 strata, constructed through a functional relationship between the income quintiles obtained in the Annual Household Survey (AHS) and the variables that were surveyed in the census. Stratum 1 corresponds to the lowest income population, while stratum 5 corresponds to the highest. The first stage of sampling in this framework will consist of about 100 to 300 primary sampling units, called primary units areas, selected with a probability proportional to size, the measure of size being the total number of dwellings.

A sample of 1,487 dwellings is proposed. In each primary unit area, a number of dwellings will be selected to be visited by enumerators, who will make a list of all members residing in the dwelling (regardless of whether they are from the same household) and select a member aged ≥18 years to proceed with the survey. This last selection is a 3rd and final sampling stage that will define the sample of 1487 participants to be tested. The sample size was calculated based on the estimated probability of pre-infection for each of the municipalities and localities participating in the survey.

Inclusion Criteria:

• - Age ≥18 at the time of signing the informed consent.
• - Resident of the Buenos Aires metropolitan area

Exclusion Criteria:

• To be ≤17 years old.
• Inability to give informed consent.

A two-stage stratified design will be used. The primary sampling units will be mostly defined as the census tracts of the 2010 national population, household and housing census. It has 5 strata, constructed through a functional relationship between the income quintiles obtained in the Annual Household Survey (HHS) and variables that were surveyed in the census. Stratum 1 is the lowest income population, while stratum 5 corresponds to the highest. The first stage of sampling in this framework will be made up of nearly 100 to 300 primary sampling units, called UP areas, selected with probability proportional to size, the measure of size being the total number of dwellings. A sample size of 1487 dwellings is proposed.