US health authorities confirm Zika birth defects

The mosquito-borne Zika virus causes birth defects, including a syndrome in which babies are born with unusually small heads, US health authorities confirmed Wednesday after months of debate and uncertainty.

“Scientists at the Centres for Disease Control and Prevention have concluded, after careful review of existing evidence, that Zika virus is a cause of microcephaly and other severe foetal brain defects,” said a statement from the federal agency.

The decision was based in part on a series of studies in Brazil, where thousands of babies were born in 2015 with birth defects, coinciding with a spike in Zika virus infections among the general public.

“This study marks a turning point in the Zika outbreak,” said CDC chief Tom Frieden. “It is now clear the virus causes microcephaly.”

There was no “smoking gun”, or single piece of evidence that offered conclusive proof, said the full report, published in the New England Journal of Medicine. Rather, the decision was made based on “increasing evidence from a number of recently published studies and a careful evaluation using established scientific criteria”, said the CDC.