Children infected with the Zika virus during infancy may be at risk of suffering brain damage, according to a recent study on primates published in Science Translational Medicine.
The Zika virus has been shown to destroy developing brain tissue when it infects a fetus in the womb. However, scientists know far less about how Zika might affect an infected infant's brain after birth.
In the study, researchers infected rhesus macaques with the Zika virus when they were around one month old, which corresponds to about three months of age in a human infant. Of the eight macaques examined in the study, six were infected with Zika virus while two others were used as controls.
The study authors followed four of the animals — the controls and two infected macaques — until they were one year old to see if the brain changes persisted and if they altered behavior. The macaques showed troubling brain and behavioral changes.
The brains of the infected animals developed differently than the brains of the controls, said senior study author Ann Chahroudi, MD, PhD, according to STAT. For example, growth of the hippocampus, which is section of the brain that helps regulate emotions and is involved in long-term memory and spatial navigation, was stunted in the infected animals.
The researchers gave the macaques a standardized stress test, called the human intruder test, to identify any significant changes. First, the animals were exposed to a stranger, seen first in profile. Later the person made eye contact with the macaques. The study's control animals were scared, which is how they ought to have behaved, according to Dr. Chahroudi. The animals infected with the Zika virus during infancy were more inward focused and did not exhibit behavior suggesting fear, Dr. Chahroudi said.
Dr. Chahroudi acknowledged given the small numbers of animals in the study, one must be cautious about drawing firm conclusions about what the research can say about Zika infection in infants.
To see if there is a cutoff point after which Zika infection no longer leads to changes in the animals' brains, Dr. Chahroudi said she would like to complete another study where macaques are infected at different ages.