Objective: To identify newborns with congenital Zika infection (CZI) at a maternity hospital in Salvador, Brazil, during the 2016 microcephaly outbreak. Methods: A prospective study enrolled microcephalic and normocephalic newborns with suspected CZI between January and December 2016. Serology (immunoglobulins IgM and IgG) and quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) for the Zika virus were performed. Demographic and clinical characteristics of newborns with and without microcephaly were compared.Results: Of the 151 newborns enrolled, 32 (21.2%) were classified as microcephalic.The majority of these cases were born between January and May 2016. IgM and IgG Zika virus antibodies were detected in 5 (23.8%) and 17 (80.9%) microcephalic newborn blood samples, respectively. Six (24%) microcephalic newborns tested positive for Zika virus by RT-qPCR in urine or placenta samples. Thirteen (11.8%) normocephalic newborns also tested positive for Zika virus by PCR in urine, plasma, or placenta samples, while IgM antibodies against Zika were detected in 4 (4.2%) others. Conclusions:Identification of 17 normocephalic CZI cases, confirmed by IgM serology or RT-qPCR for Zika virus, provides evidence that CZI can present asymptomatically at birth. This finding highlights the need for prenatal and neonatal screening for Zika virus in endemic regions.

Background Salvador was one of the Brazilian cities most affected during the 2015 Zika virus (ZIKV) outbreak. Methods A cross-sectional study was performed with enrolment of parturients and their newborns. Results Positive IgM antibodies for ZIKV, dengue (DENV) and Chikungunya (CHIKV) were present in 6.9, 11.9 and 22.8% of the parturients, and IgG antibodies were detected in 72.3, 92.3 and 38.6%, respectively. No cases of DENV congenital infection were identified. ZIKV and CHIKV congenital infections were observed in 16.5 and 13% of newborns, respectively. Conclusions High exposure rates to the three arboviruses and the identification of newborns with ZIKV and CHIKV congenital infections reinforces the necessity of ZIKV and CHIKV prenatal and neonatal screening in endemic regions.

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