NEW YORK (NYTIMES) - As the first babies born with brain damage from the Zika epidemic become two-year-olds, the most severely affected are falling further behind in their development and will require a lifetime of care, according to a study published on Thursday (Dec 14) by the Centres for Disease Control and Prevention.
The study, the first to comprehensively assess some of the oldest Zika babies in Brazil, focused on 15 of the most disabled children born with abnormally small heads, a condition called microcephaly.
At about 22 months old, these children had the cognitive and physical development of babies younger than six months. They could not sit up or chew, and they had virtually no language.
"A child might be making those raspberry sounds, but they are not making even the sort of consonant sounds like 'mama, baba, dada,'" said Georgina Peacock, an author of the study and the director of the division of human development and disability at the CDC's National Centre on Birth Defects and Developmental Disabilities.
It is unclear how many of the nearly 3,000 Brazilian Zika babies born with microcephaly will have outcomes as severe as the children in the study, but the experiences of doctors working in Brazil suggest it could be hundreds.
"It's heartbreaking," said the CDC director Brenda Fitzgerald.
"We would expect that these children are going to require enormous amounts of work and require enormous amounts of care."
The new study, conducted with the Brazilian Ministry of Health and other organisations, evaluated children in Paraiba state, part of Brazil's northeastern region, which became the epicentre of the Zika crisis.
The researchers initially studied 278 babies born in Paraiba between October 2015 and the end of January 2016. Of those, 122 families agreed to participate in follow-up evaluations this year. The study released on Thursday involves what were considered the most severe of those cases, Peacock said.
The children were evaluated when they were between 19 and 24 months old. Four of the 19 evaluated had very few symptoms or developmental difficulties, and researchers concluded they were "misclassified" as Zika babies, possibly because of errors in lab testing or head measurement.
But 15 children, eight girls and seven boys, had a range of symptoms, most of which had not improved since infancy. All had severely impaired motor skills, with all but one child meeting the conditions for a diagnosis of cerebral palsy.
Most had seizures and sleeping problems. Eight had been hospitalised at some point, most for bronchitis or pneumonia. Nine had difficulty eating or swallowing, which can be life-threatening because food can get stuck in the lungs or the children can be malnourished.
Most had vision and hearing problems serious enough to impede their ability to learn and develop, Peacock said.
"Children wouldn't turn to the sound of a rattle or they wouldn't be able to follow an object, which typically a child can do by six to eight weeks of age," she said.
"What we suspect is that because they have experienced so much damage to the brain, that connection of an object being presented and being transmitted to the back of the brain is not happening, so that is a significant cognitive impairment."
Brazilian doctors not involved in the study say it matches their experience.
"Our results are similar to this study," said Dr Camila Ventura, head of clinical research at the Altino Ventura Foundation, which provides physical therapy, vision care and other services to its registry of 285 Zika babies in Pernambuco state.
She and colleagues are evaluating their patients in conjunction with the National Institutes of Health, and she said a pilot study of 40 toddlers found they are not babbling or making language sounds, many cannot even swallow regular milk, some need gastric tubes and only two of the 40 are walking.
"The others are having trouble even holding their heads up," she said.
Now, the number of babies being born with complications from Zika has decreased as people in the region gain immunity after having been bitten by infected mosquitoes during the crisis and as some women are taking precautions to prevent infection during pregnancy.
Nevertheless, Dr Ernesto Marques, an infectious disease expert at the University of Pittsburgh and the Oswaldo Cruz Foundation in Recife, said about 3 per cent of 1,000 pregnant women in a recent sample were infected with Zika.
"The problem's not going away," he said. "We are still having cases."
In the continental United States, there have been 98 live births and nine pregnancy losses involving birth defects associated with Zika, the CDC said. In the US territories, there have been 142 live births and eight pregnancy losses.
The CDC is following nearly 7,000 pregnant women with evidence of Zika infection in the United States and its territories. "We certainly have seen decreased cases, but it's not zero," Dr Fitzgerald said.
In Brazil, the future of Zika babies is complicated by poverty and strained resources.
"Most of these babies are from low socioeconomic status and rely on the public health system to provide care," Marques said. "It's very difficult to manage those children because they need multiple types of specialists."
He said the most promising interventions include vision therapy and glasses provided to babies by the Altino Ventura Foundation and Botox injections that have helped relax rigid muscles.
Peacock said one bright spot is that many babies have outgrown their early intense crying and irritability and seem to be able to soothe themselves or be calmed by their mothers.
In some of the severe cases, however, treatment like physical and occupational therapy can only really make the children more comfortable, not improve their development.
"These are the worst of our fears," Fitzgerald said.
CDC officials want to monitor the Zika babies for years to understand the range of difficulties and see if problems develop for more mildly affected children and "children who at this point appear normal," Fitzgerald said.
"We need to keep working on this issue and we need to be trying to figure out what's going on with these babies."