Unrecognized Dengue Transmission in Socially Vulnerable Peri-Urban Neighborhoods of a Temperate Argentine City: Integrating Serology with Knowledge, Attitudes, and Practices.

Background/Objectives: Dengue is an emerging arboviral disease in temperate South America, where urban expansion, climate variability, and social vulnerability favor transmission. In Argentina, the endemic circulation of dengue was established in the late 1990s and outbreaks are reported every three or four years. Methods: This cross-sectional study assessed dengue virus (DENV) seropositivity and associated sociodemographic, environmental, and knowledge-attitudes-practices (KAPs) factors in three socioeconomically vulnerable peripheral neighborhoods of Santa Fe, Argentina, between December 2019 and March 2020. Results: A total of 188 adults were surveyed and tested for anti-DENV IgG using ELISA. KAPs questionnaires and direct peridomiciliary observations were used to characterize exposure contexts. Apparent seropositivity was 16.5%, with an adjusted estimate of 10.7% after accounting for test performance, indicating substantial unrecognized DENV circulation. Most seropositive individuals had no previous dengue diagnosis, highlighting underdetection likely related to asymptomatic infections, limited healthcare access, or surveillance gaps. Although dengue awareness was high (98.4%), knowledge was often incomplete and was weakly correlated with preventive practices, suggesting that awareness alone does not translate into effective risk reduction under structural constraints. In multivariate analysis, living farther from vacant lots was associated with higher odds of seropositivity, consistent with transmission concentrated in denser urban settings. Conclusions: Integrating serology with KAPs surveys provides critical insights into hidden transmission and supports targeted surveillance and public health interventions in vulnerable urban settings.