Zika Virus Causes Severe Brain Defects, CDC Confirms

Government scientists reported Wednesday they have determined that the Zika virus causes severe defects in unborn children, including microcephaly, which leaves babies with abnormally small heads and often with brains that do not develop properly.

The findings were published in the New England Journal of Medicine by scientists at the Centers for Disease Control and Prevention. The link has long been suspected but Wednesday's announcement is the first time scientists have definitively linked the tiny bite of a mosquito to a worldwide outbreak that is expected to infect 4 million people this year.

"This study marks a turning point in the Zika outbreak," CDC director Tom Frieden said in a press release. "It is now clear that the virus causes microcephaly.

"We are also launching further studies to determine whether children who have microcephaly born to mothers infected by the Zika virus is the tip of the iceberg of what we could see in damaging effects on the brain and other developmental problems."

Zika is transmitted via mosquito bites and sexual contact, the CDC says. The World Health Organization has declared an international public health emergency and advised pregnant women against traveling to about 30 countries, moslty in the Carribbean and Latin America.

People can get the virus traveling to countries where mosquitos carry Zika or through sexual contact with someone who has become infected. No cases of mosquitos in the United States transmitting the virus have been reported.

You can see a full list of countries that the CDC has put under travel advisory here.

The center stressed that not all expecting mothers who get the virus will have children with birth defects. This exact rate, along with a host of other issues about the relatively new virus, still have yet to be determined.

"While one important question about causality has been answered, many questions remain," the CDC press release says.

"Answering these will be the focus of ongoing research to help improve prevention efforts, which ultimately may help reduce the effects of Zika virus infection during pregnancy."

The virus is relatively harmless for men or women who aren't pregnant. People with Zika can get a fever, rash or joint pain for a few days before it goes away.