Excerpts from a report by the Australian Broadcasting Corporation on the Brazilian survey showing Zika is not the cause of microcephaly:
A four-year survey of more than 100,000 newborn babies in north-eastern Brazil has uncovered hitherto unrecognised patterns of microcephaly.
The discovery suggests microcephaly is not necessarily a new phenomenon, and questions whether Zika virus is even the cause.
The scramble in Brazil to discover the cause led paediatric cardiologist Dr Sandra Mattos to realise she was sitting on a database which could provide some answers.
Over four years, she and her colleagues surveyed more than 100,000 newborns for congenital heart disease in the Brazilian state of Paraiba.
But importantly, in just over 16,000 of these babies, the nurses also collected other information, such as length, weight, and head circumference — the indictor for microcephaly.
“We tried to establish the pattern of microcephaly over the last four years,” Dr Mattos said.
Dr Mattos and her colleagues were surprised by the numbers.
“What we expected was that we would have something like three to four cases a year of microcephaly — that is what has been documented in the official sites.
“But we then noticed that we had much, much higher numbers.”
As part of the survey, Dr Mattos’ team assessed head size in three ways to ensure it was as accurate as possible.
“Independent of what criteria we used, we had between 2–8 per cent of babies that would fall into the criteria of microcephaly,” she said.
This represents between 2,000 and 4,000 babies per year in the state of Paraíba — about 1,000 times more than the team expected.
The survey calls into question whether these microcephaly cases are caused by Zika virus or something else.
If it is Zika virus, it has been in Brazil for a lot longer than people have thought, but that does not explain why after 50 years Zika has only now been linked to microcephaly.