Zika infection in the womb can damage a fetal brain. But can the insidious virus also attack the still-developing brains of newborns?
The National Institute of Allergy and Infectious Diseases said Monday that scientists would try to answer that question by carrying out the first large such study to be funded by the agency.
Several hundred infants in Guatemala, where Zika is still circulating, will be examined for at least a year and will be compared with another group of children younger than 5.
“We are enrolling infants in the first three months of life and their mothers … to really try to understand what happens to these babies in terms of their neurologic and neurodevelopmental growth and effects if they get infected with Zika in very early life,” Dr. Flor Muñoz, a professor of pediatric infectious diseases at Baylor College of Medicine, in Houston, told STAT.
The Centers for Disease Control and Prevention has reported that children, like adults, mainly have very mild symptoms when they contract Zika.
But there is reason to believe infection might be unsafe for the brains of infants. The virus is neurotropic — it is drawn to and attacks cells in the central nervous system. The brain of a young child continues to develop in the first couple of years after birth.
A case in Brazil last year raised concerns about the impact of Zika on infants. A baby born to a woman infected during pregnancy appeared normal, although it had Zika virus in its blood at birth and for a couple of months afterwards. As time passed, the baby developed some of the problems seen with congenital Zika syndrome. But it wasn’t clear if the damage occurred in the womb or if the virus continued to attack the brain after birth.
If it turns out that Zika infection in infancy is dangerous to developing brains, the current advice that pregnant women avoid traveling to places where Zika is spreading would likely be expanded to include young children as well.
Muñoz said the researchers have already started enrolling babies in the trial. They will monitor the development of the babies’ head circumference, test their hearing and vision, and assess their general development.
“This natural history study of Zika among Guatemalan children promises to yield valuable insights into acute and longer-term outcomes of infection,” said Dr. Anthony Fauci, NIAID’s director. “It is imperative that we understand the potential neurologic and neurodevelopmental outcomes of Zika virus infection in children infected in infancy and early childhood.”
In addition, researchers hope to be able to figure out if young children who contract Zika have more severe disease if they have previously been infected with the related dengue virus. Among the infants, they will be looking to see if babies born to women who have been previously infected with dengue — and therefore have antibodies that they pass on to the fetus in the womb — have more complications if they contract Zika.
The concept that prior infection with dengue might lead to more severe Zika is called antibody dependent enhancement.
Muñoz and Dr. Edwin Asturias, of the University of Colorado Department of Pediatrics and Center for Global Health, will lead the study. Their Guatemalan collaborators work at a nonprofit foundation in Coatepeque, in southwestern Guatemala, that runs a clinic for young children.
The study is expected to take about three years, but Muñoz said the research team hopes to have some preliminary answers within about a year.