Dropping previous caution about the relationship between the Zika virus and the birth defect microcephaly, scientists said Wednesday there is no longer any doubt that Zika causes infants to be born with abnormally small heads and damaged brains.
The announcement marks a "turning point in the Zika outbreak," said CDC Director Tom Frieden, MD, adding that the findings would be published later Wednesday in the New England Journal of Medicine.
"The science now shows what the hundreds of impacted families have suspected all along. Zika virus is the cause of the tragic increase in microcephaly cases and other serious brain defects," Frieden said.
Though the virus had been strongly suspected to cause microcephaly and other serious birth defects, scientists had been careful to say that they didn't yet know whether the appearance of the two things together could be just a coincidence or whether it was a cause-and-effect relationship.
But in a press briefing, experts said there was now enough scientific evidence to prove that Zika causes microcephaly. By clearly laying out that evidence, scientists hope to dispel still-swirling rumors that other agents, such as a chemical that kills mosquito larvae, might be behind the outbreak of microcephaly, which was declared a worldwide public health emergency by the World Health Organization in February.
Experts said they also hoped the strong statement would serve as a wake-up call to Americans who aren't very worried about the Zika infection, at least according to recent surveys.
"My hope is that now that we can be more convincing that Zika virus does cause these severe birth defects in babies, that people will focus on our prevention messages more carefully," said Sonja A. Rasmussen, MD, director of the Division of Public Health Information Dissemination at the CDC.