From Epidemic to Endemic: Longitudinal Surveillance of Congenital Zika Syndrome in Brazil

Zika virus (ZIKV) emerged in Brazil in 2015, causing an unprecedented epidemic of Congenital Zika Syndrome (CZS). A decade later, longitudinal analyses evaluating temporal trends and subnational heterogeneity in CZS burden remain limited. Using publicly available data from SINAN/DATASUS and the RESP-Microcephaly registry (SVS/Ministry of Health, updated July 2024), we conducted a descriptive ecological analysis of ZIKV infection and CZS in Brazil from 2015 to 2023. Of 331,309 notified Zika cases (2015-2023), 213,350 occurred in 2016, followed by an 91.75% decline in 2017 and sustained low-level endemic circulation thereafter. Among 3,751 confirmed microcephaly cases, 1,828 were confirmed with ZIKV etiology. The Northeast region accounted for 75.4% of confirmed cases despite representing approximately 27% of the national population. State-level analyses revealed distinct epidemiological patterns, including persistent microcephaly notifications of non-Zika etiology in Minas Gerais and continued detection of ZIKV-attributed CZS in Amazonas and Goias through 2023. These findings highlight pronounced geographic disparities in congenital Zika burden, reflect significant heterogeneity in diagnostic capacity, and underscore the need for sustained surveillance and systematic etiological investigation of congenital abnormalities in the post-epidemic era.