A 'Healthy' Baby With Developmental Delay: Could It Be Zika?

Cynthia A. Moore, MD


January 06, 2020


This infant was born to a woman with possible Zika virus exposure during pregnancy; no laboratory testing was done for either the mother or the infant. If findings consistent with congenital Zika virus infection are not apparent, typically no evaluation is recommended outside of the standard evaluation. Because this infant is now presenting with abnormalities associated with congenital Zika virus infection, recommended evaluation would fall under the category of infants with findings consistent with CZS, regardless of maternal Zika virus testing.

According to CDC's guidance, in addition to a standard evaluation, recommendations include Zika virus laboratory testing, a head ultrasound, AABR (if the newborn hearing screen by OAE methodology only was passed), and a comprehensive ophthalmologic examination performed by 1 month of age to detect subclinical brain and eye findings. Although this infant is now 3 months old, she received appropriate evaluation for brain and eye anomalies after showing signs of visual impairment.

Laboratory testing of infants for Zika virus should be performed as early as possible, preferably within the first few days after birth. Testing includes concurrent Zika virus NAAT in infant serum and urine and Zika virus IgM testing in serum. If cerebrospinal fluid (CSF) is obtained for other purposes, Zika virus NAAT and Zika virus IgM testing should be performed on CSF. Although positive Zika testing results for RNA and IgM within the first few weeks to months after birth have been demonstrated in rare circumstances, NAAT in a 3-month-old infant with possible congenital exposure is less likely to be positive than Zika-specific IgM testing.

Ordering a Zika virus NAAT for the mother and father would not be an appropriate next step in this case. Zika virus RNA is only transiently present in body fluids; a negative NAAT does not rule out infection.

Because this infant is only 3 months old, a PRNT would not be helpful. A positive PRNT at this age could be the result of either maternal antibody transmission via the placenta or fetal infection. After maternal antibodies wane (estimated to be at about 18 months), the infant is considered not to have congenital Zika virus infection if the PRNT results are negative. If PRNT results are positive, congenital Zika virus infection is presumed. Learn more information on laboratory testing for infants in CDC's Guidance. A repeat AABR is not recommended for infants who pass the initial hearing screening using this technology.

While it would be appropriate to refer the infant to an early intervention program because of visual findings, this is not part of the diagnostic process for infants with possible congenital Zika virus infection.

Case 3: Unknown Exposure, Postnatal-Onset Microcephaly and Developmental Delay

A mother brings her 4-month-old son to his pediatrician with concerns of irritability, poor sleep since birth, and growing concerns over the past month or two that he is not moving his left leg as much as the right. The mother states that his left leg seems stiff when she tries to bend it while dressing him; she has no concerns with how he moves his arms or right leg. She does not remember his older sister having this problem as an infant. She reports no complications during the pregnancy or delivery but reports that shortly after birth, the infant had jaundice that did not require treatment. There is no history of postnatal head trauma. The mother and father moved to the United States from South America 4 years ago.

On examination, the infant has spasticity in his left leg, mild increase in truncal tone, and preference for reaching for objects with his right hand. His head circumference at birth was at the 25th percentile; however, his head circumference at this visit has not increased since the last measurement at 2 months of age, and now plots slightly below the third percentile. He is nondysmorphic. Scores from a standardized developmental screening tool administered during this visit are abnormal for gross motor. MRI of the brain shows an isolated area of cortical dysplasia in the right hemisphere and scattered calcifications primarily in the basal ganglia.