Lessons Learned at the Epicenter of Brazil's Congenital Zika Epidemic: Evidence From 87 Confirmed Cases

Abstract

Congenital Zika virus infection has stimulated great international concern. A prospective case series of 87 infants with laboratory-confirmed congenital Zika syndrome (CZS) at the epicenter of the Brazilian Zika epidemic in Pernambuco state is presented. Mothers were interviewed for symptoms of possible Zika virus (ZIKV) infection during pregnancy, and fetal ultrasounds were obtained. Infant cerebrospinal fluid (CSF) samples were tested for ZIKV-specific antibodies, and sera were screened for other congenital infections. Neuroimaging and ophthalmologic evaluations were also performed. Sixty-six mothers (76%) reported symptoms of ZIKV infection during gestation. Fetal ultrasounds were available from 90% of the mothers, and all demonstrated brain structural abnormalities. All of the CSF samples tested positive for ZIKV immunoglobulin M. The majority of infants (89%) were term; the mean birth weight was 2577 ± 260 g, and the mean head circumference was 28.1 ± 1.8 cm. Severe microcephaly, defined as head circumference 3 SD below the mean for sex and gestational age, was found in 72 (82%) infants. All infants had an abnormal neurological exam, and 18 (20.7%) had arthrogryposis. The main abnormalities detected in computed tomography scans were calcifications (99%), followed by ventricular enlargement (94%), cortical hypogyration (81%), and less commonly, cerebellar hypoplasia (52%). Unilateral diaphragm paralysis was identified in 3 infants. Maternal young age, term infant, small for gestational age, and the presence of ophthalmologic abnormalities were significantly associated with a smaller head circumference Z score. Our findings, based on laboratory-confirmed ZIKV infection, add valuable evidence for the understanding of CZS.

Keywords: Zika virus; congenital Zika syndrome (CZS); diaphragm paralysis; immunoglobulin M.; microcephaly.