Doctors in Brazil have mapped out the largest set of brain scans of children with microcephaly, presumably caused by mothers becoming infected with the virus while pregnant.
They examined 23 youngsters and found “severe cerebral damage” which indicates a “poor prognosis for neurological function”.
Microcephaly is a rare birth defect where a baby is born with an unusually small head.
Since last October there has been a significant increase in the number of cases of microcephaly among babies born in Brazil, which has led to scientists linking the condition with the virus.
In February, the World Health Organisation (WHO) said the link between microcephaly found in babies born to infected mothers should be considered a “public health emergency of international concern”.