Spatiotemporal Distribution and Socioeconomic Disparities of Dengue, Chikungunya and Zika in Two Latin American cities from 2007 to 2017.

To assess the presence, pattern and magnitude of socioeconomic inequalities on dengue, chikungunya and Zika in Latin America, accounting for their spatiotemporal distribution.
Using longitudinal surveillance data (reported arboviruses) from Fortaleza, Brazil and Medellin, Colombia (2007-2017), we fit Bayesian hierarchical models with structured-random effects to estimate: 1) spatiotemporally-adjusted incidence rates; 2) Relative Concentration Index and Absolute Concentration Index of inequality; 3) temporal trends in RCIs; and 4) socioeconomic-specific estimates of disease distribution. The spatial analysis was conducted at the neighborhood level (urban settings). The socioeconomic measures were the median monthly household income for Brazil and the Socio-Economic Strata index in Colombia.
There were 281,426 notified arboviral cases in Fortaleza and 40,887 in Medellin. We observed greater concentration of dengue among residents of low-socioeconomic neighborhoods in both cities: Relative Concentration Index = -0.12 (95% CI= -0.13, -0.10) in Fortaleza and Relative Concentration Index = -0.04 (95% CI= -0.05, -0.03) in Medellin. The magnitude of inequalities varied over time across sites and was larger during outbreaks. We identified a non-monotonic association between disease rates and socioeconomic measures, especially for chikungunya, that changed over time. The Relative Concentration Index and Absolute Concentration Index showed few if any inequalities for Zika. The socioeconomic-specific model showed increased disease rates at median monthly household incomes below US$400 in Brazil and (au: please rephrase:) at-Socio-Economic Strata index below four in Colombia. (??) CONCLUSIONS: We provide robust quantitative estimates of socioeconomic inequalities in arboviruses for two Latin-American cities. Our findings could inform policy making by identifying spatial hotspots for arboviruses and targeting strategies to decrease disparities at the local level.

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