Clinical phenotype in infants with negative Zika virus immunoglobulin M testing born to mothers with confirmed Zika virus infection during pregnancy.

BACKGROUND: Recommended testing for both infants with Zika-associated birth defects (i.e., microcephaly and selected brain or eye anomalies) and infants without birth defects whose mothers had laboratory evidence of possible Zika virus (ZIKV) infection during pregnancy includes nucleic acid amplification testing (NAAT) and immunoglobulin M (IgM) testing within days after birth. Brain and eye defects highly specific for congenital ZIKV infection have been described; sporadic reports have documented negative ZIKV testing in such infants. METHODS: Infants from the U.S. Zika Pregnancy and Infant Registry and Zika Birth Defects Surveillance with Zika-associated birth defects and maternal and infant laboratory testing for ZIKV and two congenital infections (i.e., cytomegalovirus [CMV] and toxoplasmosis) were reviewed for phenotype and laboratory results. Infants with at least one defect considered highly specific for congenital ZIKV infection were designated as having congenital Zika syndrome (CZS) clinical phenotype for this study. RESULTS: Of 325 liveborn infants with Zika-associated birth defects and laboratory evidence of maternal ZIKV infection, 33 (10%) had CZS clinical phenotype; 172 (53%) had ZIKV IgM testing with negative or no ZIKV NAAT. ZIKV IgM was negative in the remaining 121 infants, and for 90%, testing for CMV and toxoplasmosis was missing/incomplete. Among 11 infants testing negative for ZIKV IgM, CMV, and toxoplasmosis, 2 infants had CZS clinical phenotype. CONCLUSIONS: These data add support to previous reports of negative ZIKV IgM testing in infants with clear maternal and phenotypic evidence of congenital ZIKV infection. Follow-up care consistent with the diagnosis is recommended regardless of infant ZIKV test results.

Functional Outcomes among a Cohort of Children in Northeastern Brazil Meeting Criteria for Follow-Up of Congenital Zika Virus Infection.

Following the large outbreak of Zika virus in the Western Hemisphere, many infants have been born with congenital Zika virus infection. It is important to describe the functional outcomes seen with congenital infections to allow for their recognition and appropriate interventions. We evaluated 120 children conceived during the 2015-2016 Zika virus outbreak in Paraíba, Brazil, who were approximately 24 months old, to assess functional outcomes. All children met either anthropometric criteria or laboratory criteria suggestive of possible congenital Zika virus infection. We collected results of previous medical evaluations, interviewed parents, and performed physical examinations and functional assessments, for example, the Hammersmith Infant Neurological Examination (HINE). We compared patterns of neurologic outcomes and developmental delay at age 24 months by whether children met anthropometric or laboratory criteria, or both. Among children meeting both criteria, 60% (26/43) were multiply affected (had severe motor impairment, severe developmental delay, and suboptimal HINE scores), compared with 5% (3/57) meeting only laboratory criteria and none (0/20) meeting only anthropometric criteria. Of the remaining 91 children, 49% (45) had developmental delay, with more severe delay seen in children meeting both criteria. Although children meeting physical and laboratory criteria for potential congenital Zika virus infection were more severely affected, we did identify several children with notable adverse neurologic outcomes and developmental delay with no physical findings but potential laboratory evidence of Zika virus infection. Given this, all children who were potentially exposed in utero to Zika virus should be monitored in early childhood for deficits to allow for early intervention.