The New York Times – It is the news that doctors and families in the heart of Zika territory had feared: Some babies not born with the unusually small heads that are the most severe hallmark of brain damage as a result of the virus have developed the condition, called microcephaly, as they have grown older.
The findings were reported in a study of 13 babies in Brazil that was published Tuesday in Morbidity and Mortality Weekly Report. At birth, none of the babies had heads small enough to receive a diagnosis of microcephaly, but months later, 11 of them did.
For most of those babies, brain scans soon after birth showed significant abnormalities, and researchers found that as the babies aged, their brains did not grow or develop enough for their age and body size. The new study echoes another published this fall, in which three babies were found to have microcephaly later in their first year.
As they closed in on their first birthdays, many of the babies also had some of the other developmental and medical problems caused by Zika infection, a range of disabilities now being called congenital Zika syndrome. The impairments resemble characteristics of cerebral palsy and include epileptic seizures, muscle and joint problems and difficulties swallowing food.
“There are some areas of great deficiency in the babies,” said Dr. Cynthia Moore, the director of the division of congenital and developmental disorders for the Centers for Disease Control and Prevention and an author of the new study. “They certainly are going to have a lot of impairment.”
Dr. Deborah Levine, a professor of radiology at Harvard Medical School who has studied Zika but was not involved in either study, said there would most likely be other waves of children whose brains were affected by the Zika infection, but not severely enough to be noticed in their first year.
“A lot of the developmental abnormalities we’re not going to see until later,” she said. “There’s going to be another group seen later in childhood, I’m afraid, and another group probably when they reach school age.”
In the new study, doctors at two clinics in the northeastern Brazilian states of Pernambuco and Ceará described the cases of 13 infants who had tested positive for the Zika virus. In 11 of the babies, brain scans taken days or weeks after birth showed significant neurological damage, including improperly formed brain areas, excess fluid in some places and abnormal calcium deposits, or calcification, which probably resulted from brain cell death. But the size of their heads, though small, was not small enough to be considered microcephaly. So doctors monitored their progress as they grew.
Dr. Vanessa van der Linden, another author of the study and a neuropediatrician at the Association for Assistance of Disabled Children in Recife, Brazil, where most of the babies in the study are patients, said the type of brain damage in the babies who later developed microcephaly “presented the same pattern, but less severe” than those with it at birth.
The babies in the study published this fall also appeared to have a pattern of similar, but less severe, brain damage, said Dr. Antonio Augusto Moura da Silva, of the Federal University of Maranhão and an author of that study, which was published in Emerging Infectious Diseases. He and his colleagues studied 48 babies with brain abnormalities in the northeastern state of Maranhão, identified six babies who did not have microcephaly at birth, and found that three of them later developed it.
“We were worried, but now that we’ve started following those cases, we are very sad,” Dr. Silva said. “The picture is really terrible. At the least, if they have microcephaly, we expect them to have a very poor quality of life.”
Experts and the authors of the studies said it was unclear why these infants’ brains did not develop enough to match their age and body size. Dr. Ernesto T. A. Marques Jr., an infectious disease specialist at the University of Pittsburgh and the Oswaldo Cruz Foundation in Recife, who was not involved in either study, said it could be that because of the initial fetal brain damage, “the necessary pathways and hormones that organize growth of the neonatal brain are not there anymore and the brain doesn’t grow.”
It could also be the result of the immune system responding to the original Zika virus infection. Dr. Moore said that another possibility might be that there was still some infection that continued to damage the brain. But she said that seemed less likely, given that follow-up tests for Zika virus conducted on seven of the babies did not find evidence of active infection.
The oldest babies in these studies are only just over a year old, too young for researchers to identify cognitive problems or delays in skills like speech. But some deficits are clear: Many of the babies had serious physical deficits tied to neurological damage, including overly tense muscles, muscle weakness and the inability to voluntarily move their hands.
Still, unlike many babies born with microcephaly, most of the 13 in the new study had social interaction skills like smiling and making eye contact. And eight of them had good head control, an important skill for developing the ability to sit or walk.
While cautioning that the study involved too few cases to make generalizations, Dr. van der Linden said that it appeared that most of these babies had good eye contact because the damage was less severe in brain areas involving vision than it was in areas involving motor skills.
Dr. Marques said that head control, the ability to lift and support the head without help, in babies with microcephaly was “quite rare.” Having a social smile and eye contact is less rare, he said, depending on the type of visual damage and on whether they receive enough visual stimulation to strengthen their ability to use their eyes.
“At this age, 80 percent of brain stimulus comes from the eyes,” he said. “If you don’t have that working and you lose this window of opportunity, these babies cannot recover it.”
One baby, a boy, had no anomalies at birth. His limbs looked normal and his head size was proportional to his body, Dr. Moore said. But brain scans soon after birth showed excess fluid and abnormalities in his cortex and corpus callosum, which separates the two hemispheres. At 11 months old, he had microcephaly, and also epilepsy, difficulty swallowing, involuntary muscle contractions, and muscles that were too stiff and restricted his movement, she said.
Another baby had a sloping forehead and slight depressions in the front of his head at birth, as well as similar types of brain damage, apparent on scans, Dr. Moore said. By the time he was 1, he had developed microcephaly that was among the most severe of the babies in the study, and had muscular and swallowing problems. But he also had good eye contact, researchers reported.
In six of the cases, the mothers reported having a symptom of Zika infection, a rash, between the second and fifth months of pregnancy. That supports other evidence suggesting that babies born to mothers who were infected late in the first trimester suffer the most serious effects. But since there are no symptoms in 80 percent of cases of Zika infection, it was unclear when most of the women were infected, and researchers are still unable to say whether the virus is more damaging to babies if their mothers experience symptoms.