Sociodemographic and environmental factors associated with dengue, Zika, and chikungunya among adolescents from two Brazilian capitals

Among the emerging and reemerging arboviral diseases, Zika, dengue and chikungunya deserve special attention due to their wide geographical distribution and clinical severity. The three arboviruses are transmitted by the same vector and can present similar clinical syndromes, bringing challenges to their identification and register. Demographic characteristics and individual and contextual social factors have been associated with the three arboviral diseases. However, little is known about such associations among adolescents, whose relationships with the social environment are different from those of adult populations, implying potentially different places, types, and degrees of exposure to the vector, particularly in the school context. This study aims to identify sociodemographic and environmental risk factors for the occurrence of Zika, dengue, and chikungunya in a cohort of adolescents from the Study of Cardiovascular Risks in Adolescents-ERICA-in the cities of Rio de Janeiro/RJ and Fortaleza/CE, from January 2015 to March 2019. Cases were defined as adolescents with laboratory or clinical-epidemiological diagnosis of Zika, dengue, or chikungunya, notified and registered in the Information System for Notifiable Diseases (SINAN). The cases were identified by linkage between the databases of the ERICA cohort and of SINAN. Multilevel Cox regression was employed to estimate hazard ratios (HR) as measures of association and respective 95% confidence intervals (95%CI). In comparison with adolescents living in lower socioeconomic conditions, the risk of becoming ill due to any of the three studied arboviral diseases was lower among those living in better socioeconomic conditions (HR = 0.43; 95%CI: 0.19-0.99; p = 0.047) and in the adolescents who attended school in the afternoon period (HR = 0.17; 95%CI: 0.06-0.47; p<0.001). When compared to areas whose Building Infestation Index (BII) for Aedes aegypti was considered satisfactory, a BII in the school region classified as "alert" and "risk" was associated with a higher risk of arboviral diseases (HR = 1.62, 95%CI: 0.98-2.70; p = 0.062; HR = 3.72, 95%CI: 1.27-10.9; p = 0.017, respectively). These findings indicate that living in less favored socioeconomic conditions, attending school in the morning, and having a high BII for Ae. aegypti in school's region can contribute to an increased risk of infection by Zika, dengue, or chikungunya in adolescents. The identification of residential or school areas based on those variables can contribute to the implementation of control measures in population groups and priority locations. Author summaryZika, dengue, and chikungunya are arbovirus with a wide geographic distribution that can cause serious diseases. The three pathogens are transmitted by the same vector and can present similar symptoms, hindering their identification and register. Despite the great efforts to control arboviruses diseases, Brazil still registers frequently epidemics. Scientific evidence of the association of the environment, vectors, humans, and their behaviors in the arbovirus transmission is vast, but little in know about those association in adolescents. This study focused on adolescents, a part of the population whose relationships with the social environment are different from those of adult and child populations, implying different types, and degrees of exposure to the vector, particularly in the school context. For this reason, this study aims to identify sociodemographic and environmental factors associated with Zika, dengue, and chikungunya disease in adolescents in Rio de Janeiro and Fortaleza municipalities in Brazil from 2015 to 2019. The results obtained in this study highlight factors that may be influencing the transmission of Zika, dengue and Chikungunya, enabling effective measures to be implemented in the school context to control these arboviruses.