Spatiotemporal clustering, social vulnerability and risk of congenital syphilis in northeast Brazil: an ecological study.

Background: To investigate the spatial distribution of congenital syphilis (CS) and its association to social vulnerability indexes in northeast Brazil.

Methods: This was an ecological study referring to all cases of CS and CS deaths recorded in the northeast region of Brazil from 2008 to 2015. Data were obtained from three Brazilian information systems. We examined statistical correlations between CS indicators by state and municipality and their socioeconomic and social vulnerability characteristics. We used Bayesian empirical local models to identify fluctuations of the indicators. Spatial statistical tests were used to identify spatial clusters and the municipalities at high risk of CS.

Results: The incidence of CS ranged from 2.1 cases/1000 live births (LB) in 2008 to 6.9/1000 LB in 2015, with an annual increase of 19.9% (p < 0.001). The mortality coefficient of CS ranged from 2.9/1000 LB in 2008 to 6.5/1000 LB in 2015, resulting in an annual increase of 15.1% (p < 0.001). Nine spatial clusters were identified. Cases of congenital syphilis occurred in well-defined spatiotemporal clusters and in areas with high levels of social vulnerability.

Conclusions: CS incidence is associated with social vulnerability. CS control programmes should target spatial clusters and populations with high levels of social vulnerability.