Zika Virus Disease and Congenital Zika Virus Infection

Zika virus (ZIKV) is a flavivirus primarily transmitted to humans by mosquitoes, mainly Aedes aegypti . Other commonly recognized transmission modes include sexual and intrauterine transmission. Following recognition of ZIKV transmission in Africa and Asia during the 1900s, outbreaks subsequently occurred in Pacific Island nations from 2007 and the Americas from 2015. Incidence subsequently declined, but available information suggests probable low-level ongoing transmission in parts of Africa, Asia, and the Americas with rare localized outbreaks. Most infections are asymptomatic or cause mild symptoms, with rash, fever, arthralgia, and/or conjunctival hyperemia commonly reported. Although severe disease is rare, Guillain-Barré syndrome (GBS) and other neurologic and ophthalmologic presentations have been reported. Congenital ZIKV infection can result in a variety of neonatal outcomes, ranging from asymptomatic infection to a severe and distinct pattern of anomalies. Among infants with severe outcomes, clinical findings most specific for congenital ZIKV infection include severe microcephaly with partially collapsed skull, cortical hypoplasia with abnormal gyral patterns, intracranial calcifications located between the cortex and subcortex, macular scarring with focal pigmentary retinal mottling, and arthrogryposis. Management of uncomplicated disease in adults and children is supportive. Pregnant women with laboratory evidence of possible infection should be monitored for adverse pregnancy outcomes. Infants with findings consistent with congenital ZIKV infection or born to mothers with laboratory evidence of possible ZIKV infection during pregnancy should have, in addition to standard evaluation, a head ultrasound and comprehensive ophthalmologic exam. No vaccine is available, and prevention relies on the avoidance of mosquito bites and sexual transmission of ZIKV.

A 34-year-old woman presented to the emergency room in active labor at 38 weeks and 6 days of gestation. She had recently emigrated to the United States from Brazil, where she had received prior prenatal care. Early in her pregnancy she experienced a mild illness with rash and low-grade fever for which she did not seek medical care. Her last ultrasound, performed at 30 weeks’ gestation, showed evidence of microcephaly and ventriculomegaly. She delivered her male infant by spontaneous vaginal delivery. He was born with Apgar scores of 7 and 9 at 1 and 5 minutes, respectively. Initial head circumference measurements were below the third percentile for sex and gestational age. Repeat head circumference measurements confirmed microcephaly. Weight and length were measured at the 25th and 10th percentiles, respectively. On examination, the infant was noted to have a small, irregularly shaped head and multiple contractures of both upper and lower extremities bilaterally. A head ultrasound was performed and revealed microcephaly, multiple subcortical calcifications, and ventriculomegaly. In addition, magnetic resonance imaging revealed polymicrogyria of the left frontal region and bilaterally in the temporal lobes. Given the maternal history and clinical findings in the infant consistent with congenital ZIKV infection, laboratory testing was performed. The infant’s serum and urine were negative for ZIKV ribonucleic acid (RNA) by reverse transcription–polymerase chain reaction (RT-PCR) testing, but serum was positive for ZIKV IgM, with a ZIKV plaque reduction neutralization test (PRNT) titer of 1:1280 and dengue virus (DENV) PRNT titer of 1:20. Further evaluation included an ophthalmology exam that revealed left optic nerve atrophy. The infant passes an automated auditory brain-stem response hearing test. Based on clinical findings and laboratory test results, the infant was determined to have probable congenital ZIKV infection. The infant was referred to multiple specialists including neurology, ophthalmology, orthopedics, and early intervention services for further evaluation and management.