Spatiotemporal analysis of gestational and congenital syphilis in Brazil, 2011–2022

Although the elimination of congenital syphilis (CS) by 2030 is a global target, this goal remains far from being achieved. In Brazil, despite ongoing efforts toward CS elimination, its incidence continues to increase. Previous Brazilian studies have described the spatial distribution of gestational syphilis (GS) and CS separately; however, evidence remains limited regarding the overlapping spatial and temporal patterns of both conditions, which may better identify priority areas for integrated public health interventions. Therefore, the main objective of this study was to conduct a spatial analysis of GS and CS in Brazil to identify areas with overlapping occurrences of GS and CS. This ecological study was conducted using secondary data on GS and CS notifications from 2011 to 2022. Brazilian municipalities were used as units of analysis. To avoid annual fluctuations, GS and CS crude rates were calculated by time periods (2011–2014, 2015–2018, and 2019–2022). Rates were then analyzed using spatial distribution, spatial autocorrelation (Getis–Ord Gi* statistic), and multivariate spatiotemporal risk techniques. Gi* statistic identifies geographic concentrations of high and low GS and CS detection rates (hotspots and coldspots, respectively), whereas multivariate spatiotemporal analysis enables the identification of time periods and geographic areas with higher intensities of co-occurring diseases. During the study period, 546,230 GS notifications and 248,008 CS notifications were documented, with an increase in the number of municipalities reporting notifications. The Getis–Ord Gi* statistic indicated spatial dependence in the rates across all periods. Hotspots of GS and CS detection rates were identified in all Brazilian regions, with some disappearing over time, new ones emerging, and others expanding in size. No coldspots were identified. The overlap between GS and CS clusters increased, particularly along the Atlantic coast of Brazil. Most GS/CS spatiotemporal risk zones were concentrated between 2017 and 2022. GS and CS became increasingly widespread across Brazilian municipalities, with an expansion of overlapping GS and CS hotspots over time, particularly along the Atlantic coast from the Northeast to the South. These findings highlight priority areas for geographically targeted surveillance and public health interventions.