Zika for Pediatricians: Critical Update

Matt Karwowski, MD, MPH


March 02, 2016

Editorial Collaboration

Medscape &

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Assessing the Newborn for Microcephaly

Hello. I'm Dr Matt Karwowski, a pediatrician with the Pregnancy and Birth Defects Team for CDC's 2016 Zika Virus Response. Over the next few minutes, I'll share with you what we know about Zika virus and congenital microcephaly and other birth defects. I will also provide a brief overview of CDC's guidelines for healthcare providers caring for infants and children with possible Zika virus infection.

Microcephaly is a clinical finding, not a diagnosis. In the United States, microcephaly is typically defined as an occipitofrontal circumference (OFC) below the third percentile for age and sex. However, because there isn't a standard definition, microcephaly is a difficult birth defect to monitor. An infant's OFC should be measured 24-36 hours after birth by placing a measuring tape 1-2 finger-widths above the eyebrows and wrapping it around the most prominent part of the occiput, and then recording the largest of three measurements. An etiology for microcephaly is found in about half of affected infants, with possible causes including genetic conditions, teratogens, or disruptive incidents such as ischemic events.[1]

In recent months, the Brazilian Ministry of Health has reported an increase in the number of infants born with microcephaly.[2] This increase corresponds in time and place with a widespread Zika virus outbreak, raising the possibility that congenital Zika virus infection is associated with microcephaly and perhaps other birth defects. This hypothesis is supported by recent histopathologic and epidemiologic evidence.

No Definitive Link

Intrauterine Zika virus infection has been demonstrated through the detection of Zika virus RNA in fetal brain tissue, placenta, or amniotic fluid from seven pregnancies among women with clinical signs of Zika virus infection during the first or second trimesters.[3,4,5,6] Adverse fetal and infant outcomes of these pregnancies include microcephaly, brain atrophy, cerebral and intraocular calcifications, abnormally formed or absent brain structures, and cataracts. Additional evidence comes from infants who were not tested for Zika virus, but whose mothers lived in areas with Zika virus transmission and had symptoms of Zika virus infection during pregnancy. These infants had abnormal neurologic and ophthalmologic examination findings, including hypertonia, hyperreflexia, seizures, chorioretinal atrophy, and optic nerve hypoplasia, among others.[7,8,9,10,11]

Although there is increasing evidence of an association between congenital Zika virus infection and microcephaly or other birth defects, the evidence is not yet definitive. We don't know the frequency or spectrum of adverse pregnancy and pediatric outcomes, whether the timing of infection during pregnancy or severity of maternal infection correlates with the occurrence of adverse outcomes, or whether other factors play a role.

Exposure and Risk

Now that we have reviewed microcephaly and other adverse outcomes and their possible link with Zika virus, I'll briefly review CDC's updated "Interim Guidelines for Health Care Providers Caring for Infants and Children with Possible Zika Virus Infection."[12] These guidelines were published on February 19, 2016, in CDC's Morbidity and Mortality Weekly Report, are accessible online, and will be updated as more information becomes available.

There are several risk factors for Zika virus infection in infants and children.[12] Infants born to mothers with possible Zika virus exposure during pregnancy might be at risk for congenital Zika virus infection. Mothers with possible Zika virus exposure during pregnancy include those who have traveled to or lived in areas with local Zika virus transmission, or who had sex without a condom with a male partner who traveled to or lived in an affected area. Infants born to women who traveled to or lived in an affected area within 2 weeks of delivery are at risk for perinatal infection. Infants and older children who have traveled to or lived in an affected area within the past 2 weeks are at risk for Zika virus through mosquito-borne transmission. Adolescents might also be exposed to Zika virus through sexual contact with a male partner who traveled to or lived in an affected area.

Evaluation and Management

Based on limited data, clinical manifestations in children are similar to those in older age groups and most commonly include rash, fever, nonpurulent conjunctivitis, and arthralgia.[13,14,15,16,17,18,19] Although arthralgia is difficult to assess in infants and young children, suggestive examination findings include refusal to move an affected limb, pain on palpation or with passive range of motion, abnormal gait or limp in ambulatory children, and irritability. The spectrum of Zika virus disease in newborns infected perinatally is unknown at this time. Based on current evidence, Zika virus disease in children is typically mild and self-limited. Hospitalization and death are rarely reported.[19,20,21] Treatment for Zika virus disease is supportive and there is currently no vaccine available. Healthcare providers can help families avoid Zika virus exposure in affected areas by providing information about preventing mosquito bites.

All arboviral illnesses, including Zika virus, are nationally notifiable diseases. Healthcare providers should report suspected cases of Zika virus infection to their local, state, or territorial health departments. For detailed guidance on the evaluation and management of Zika virus infection in infants and children, please find CDC's latest interim guidelines at For more information on Zika virus, please visit

Web Resources

CDC Zika website

CDC: Avoid Mosquito Bites

CDC: All Countries and Territories with Active Zika Virus Transmission

ASTHO: From S/T Health Departments: Zika