Experts Now Agree That Zika Can Cause Microcephaly

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A woman in Recife, Brazil, feeds her son who has microcephaly.
A woman in Recife, Brazil, feeds her son who has microcephaly.Photo: Mario Tama

Yesterday, the World Health Organization announced that there is “a strong scientific consensus” that the Zika virus is a cause of both the birth defect microcephaly and the neurological disorder Guillain-Barré syndrome.

In February, the agency had said the link between Zika infection in pregnancy and microcephaly was “strongly suspected”; last week they said it was “highly likely” to be a cause. Researchers thus far have found evidence of the Zika virus in the brains of stillborn and aborted fetuses with microcephaly, but they haven’t been able to pin down just how often a pregnant woman with Zika will pass the virus to her offspring, or whether it’s more common if infection happens earlier in a pregnancy, rather than later.

The Centers for Disease Control and Prevention agree with the WHO that there’s enough evidence to connect the two. Still, the new declaration doesn’t mean that all people who contract the mosquito-borne virus (or their growing fetuses) will develop a health problem.

As Anne Schuchat, MD, deputy director of the CDC, told NPR: “At this point the most pressing question people want answered is, ‘If I get a Zika infection during pregnancy what are the chances my baby is going to be affected?’ We really feel a sense of urgency to both answer that question and to help stop the spread of the virus.”

While the mosquitoes that carry the virus could come to the United States, infectious-disease experts don’t believe that we’d have a large-scale outbreak like in Central and South America, thanks to better housing construction, and air-conditioning and window screens that keep the bugs out of our homes. Mosquitoes aside, the virus can be sexually transmitted from men to women, and the CDC wants to be prepared for the worst-case scenario. Today they’re holding a conference to discuss preparedness and coordinated response.

But we wouldn’t blame you if chose to bathe in bug spray this summer.