Prevalence of antibodies against dengue virus in the city of Buenos Aires: Results of a probabilistic population survey.

Objective: Dengue is a rapidly growing global health issue. In Argentina, the disease burden is primarily based on case reports or retrospective series; however, there are no prospective probabilistic studies available. To estimate the seroprevalence of antibodies against the dengue virus (DENV) in adult residents of Buenos Aires, at the end of the 2023 season, which culminated in Argentina's largest recorded dengue outbreak, and immediately before the subsequent outbreak at the beginning of 2024.

Methods: A stratified, multi-stage probabilistic population survey was conducted to ensure representativeness of the adult population of Buenos Aires, considering geographical and socio-economic diversity.The survey determined the seroprevalence rate of DENV IgG and IgM antibodies using a rapid chromatographic immunoassay. Antibody positive participants were invited for re-testing to confirm antibody result using an enzyme-linked fluorescence assay (ELFA) technique.

Results: Out of a sampling frame of 2,998 selected households, the interviewers visited 100% of the residences. The overall response rate was 26.8%. A total of 804 participants were enrolled, representing the city's 2.38 million adult population. Weighted estimates showed a total of 193,707 people aged 18 and over have antibodies to DENV. This implies a weighted prevalence [95% CI] of 8.12% [8.08%-8.15%]. The prevalence varied across different areas of the city. In the slums, the overall prevalence was twice as high (14.7% [14.5%-14.9%]) compared to the rest of the city (7.67% [7.63%-7.70%]).

Conclusion: Seroprevalence results in adults in Buenos Aires show a moderate DENV infection rate, although still far from the thresholds usually considered for initiating a mass vaccination campaign. These results underscore the need for frequent surveys.