Infants with congenital Zika virus infection who do not have microcephaly at birth can develop it months later, according to a new study.
“These findings demonstrate the importance of early neuroimaging for infants exposed to Zika virus prenatally and the need for comprehensive medical and developmental follow-up,” authors said in Tuesday’s Morbidity and Mortality Weekly Report.
Researchers from Brazil and the Centers for Disease Control and Prevention (CDC) studied 13 infants in Brazil with laboratory evidence of congenital Zika virus infection and normal head size.
While the infants did not meet the criteria for microcephaly at birth, all had brain abnormalities such as decreased brain volume and subcortical calcifications, according to the report. As early as 5 months of age, their head growth decelerated, and 11 were diagnosed with microcephaly.
“The decrease in head growth might be the consequence of earlier in utero destruction of neuroprogenitor or other neural cells, persistent inflammatory response-associated molecules, or continued infection of neural cells,” authors said in the study.
The infants also displayed “significant neurologic dysfunction, including hypertonia and hemiparesis, dyskinesia/dystonia, dysphagia, epilepsy, and persistence of primitive reflexes,” according to the report.
Infants with congenital Zika virus infection who do not have microcephaly at birth can develop it months later.
More than 60% had epilepsy and all had significant motor disabilities. They were too young for a cognitive assessment.
The CDC emphasized the importance of its previous recommendations calling for all infants whose mothers were infected with Zika during pregnancy to have a comprehensive physical exam, neurologic assessment, postnatal cranial ultrasound, standard hearing screen and Zika testing.
Babies who are found to be infected also should have a comprehensive eye exam and hearing assessment by auditory brainstem response testing before 1 month of age regardless of whether abnormalities are apparent at birth.
If abnormalities are detected, infants will need to be evaluated by an infectious disease specialist, neurologist, endocrinologist, ophthalmologist and geneticist. The primary care pediatrician and these specialists will need to provide coordinated, ongoing examinations, which are detailed in the guidance.
Those who are not born with obvious, identifiable abnormalities will need careful monitoring and screening for any that may present later in life such as those resulting in seizures or trouble with vision or hearing.
Zika virus has spread to more than 45 countries in Central and South America. In U.S. states, there have been 4,255 cases of Zika including 1,087 pregnant women. In U.S. territories, there have been 32,068 cases including 2,451 pregnant women.
Last week, a World Health Organization committee removed the designation of Zika as a Public Health Emergency of International Concern. However, it said in a news release the virus and associated birth defects “remain a significant enduring public health challenge requiring intense action.”
The CDC continues to update its recommendations on testing and caring for patients with suspected Zika infection. It recently released revised guidance for laboratories that are testing for Zika as well as an interactive Pregnancy and Zika Testing Clinical Algorithm for clinicians.
Pediatricians should report suspected congenital Zika cases to their state, local, tribal or territorial health officials and provide clinical information to the U.S. Zika Pregnancy Registry or Puerto Rico Zika Active Pregnancy Surveillance System through age 1 year so the CDC can monitor outcomes and adjust recommendations accordingly.