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Abstract Northeast Brazil was the first region to detect a significant increase in babies born with microcephaly associated with prenatal zika virus infection in 2015. Rio Grande do Sul (RS) state was less impacted due to the temperate climate preventing the spread of the vector. This study investigated the prevalence and etiology of congenital microcephaly in RS in two different periods. This cross-sectional descriptive study included all live births with congenital microcephaly in RS from 2015 to 2022. Cases were divided into two groups: P1 “outbreak” (2015-16); and P2 “endemic” (2017-22). There were 58 cases of microcephaly (3.8/10,000) in P1 and 148 (1.97/10,000) in P2. Congenital Zika Virus infection was the etiology in 5.2% (n=3) in P1 and 6.7% (n=10) in P2. In conclusion, although the ZIKV outbreak in Brazil has receded, RS remains an area of concern, with a possible slight increase of live births with microcephaly secondary to ZIKV prenatal infection relative to the number of cases due to congenital infections. The broader distribution of the vector Aedes aegypti with warmer temperatures in our state might be linked to the increase in recent years. This study can be an alert to other regions of temperate or subtropical climates.

Abstract. Objective:. Prenatal infection with the Zika virus (ZIKV) can lead to congenital Zika syndrome (CZS), characterized by microcephaly and brain injury. However, there are questions regarding the prevalence of microcephaly/CZS after the ZIKV outbreak in defined geographic areas. This study aimed to identify adverse outcomes in live births of fetuses exposed in utero to the ZIKV, compared to unexposed births, as well as maternal sociodemographic, delivery, and birth characteristics. Methods:. Here, we conducted a cross-sectional observational study to investigate the characteristics of all live births in the city of Tangará da Serra, Mato Grosso, Brazil, in 2016, after the outbreak of ZIKV infection in late 2015. All live births of children to women residing in the municipality of Tangará da Serra between January 1 and December 31, 2016, were evaluated, and head circumference was measured at birth and after 24 hours. Children born with microcephaly or a maternal history of confirmed or suspected prenatal ZIKV infection were evaluated by a multidisciplinary team. The outcomes of the exposed and non-exposed children were compared. Prevalence ratios and their respective 95% confidence intervals were calculated for sociodemographic, delivery, and live birth characteristics. Results:. Of 1,441 live births, 106 (7.3%) were from mothers with confirmed or highly probable exposure to ZIKV. The prevalence of severe congenital microcephaly (41.7/10,000) in Tangará da Serra in 2016 was ten-fold higher than that in Latin America before 2015. Conclusion:. This study may serve as a model to investigate possible outbreaks of infections in a defined geographical space in the future.

Introduction: Microcephaly is a clinical finding that can arise from congenital anomalies or emerge after childbirth. Maternal infections acquired during pregnancy can result in characteristic brain damage in the newborn (NB), which may be visible even in the fetal stage. Objective: To describe the epidemiological profile of newborns with reported microcephaly and diagnosed with congenital infections in the state of Rio Grande do Sul between 2015 and 2017. Method: A cross-sectional study was carried out on data collected from the Public Health Event Registry as well as from medical records. The investigation included serologies for toxoplasmosis and rubella; polymerase chain reaction (PCR) for Zika virus (ZIKV) in the blood and cytomegalovirus in the urine; non-treponemal tests for syphilis; and brain imaging tests. Results: Of the 257 reported cases of microcephaly, 39 were diagnosed with congenital infections. Severe microcephaly was identified in 13 patients (33.3%) and 51.3% of the cases showed alterations in brain imaging tests. In relation to the diagnosis of congenital infections, three patients (7.7%) were diagnosed with ZIKV, nine (23.1%) with cytomegalovirus, nine (23.1%) with toxoplasmosis, and 18 (46.1%) with congenital syphilis. The three cases of ZIKV showed calcification in brain imaging tests, signs of arthrogryposis, excess occipital skin and irritability, characterizing the typical phenotype of ZIKV infection. Conclusion: Most cases of congenital infection had severe neurological lesions, particularly the cases of ZIKV, which can cause neurodevelopmental delays and sequelae in these infants throughout early childhood. Keywords: Microcephaly; Congenital Infection; Zika Virus