Zika Virus Causes Birth Defects, CDC Says

It's official.

For the first time since Zika became an international buzzword, researchers are saying the virus actually causes birth defects and brain abnormalities, such as microcephaly. Until now, experts have been careful to only say there's a link between the two, not cause and effect.

In a special report published online by the New England Journal of Medicine (NEJM), experts from the Centers for Disease Prevention and Control (CDC) reviewed all available data on prenatal Zika infection (aka when a pregnant mother is infected with Zika virus) and birth defects. Based on their review of the data, the CDC researchers "conclude that a causal relationship exists between prenatal Zika virus infection and microcephaly and other serious brain anomalies."

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This development will make people take Zika virus and its prevention more seriously, the authors write in the report. So far, the 346 cases of the virus in the United States have only come from travel and sexual transmission, meaning people have become infected when they traveled to other countries or had sexual contact with someone who was infected. The United States has yet to see a locally-transmitted case; however, the CDC announced its concerns about that possibility in a press conference at the White House on Monday, with CDC Principal Deputy Director Anne Schuchat's extremely quotable comment that "Everything we look at with this virus seems to be a bit scarier than we initially thought."

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The authors of the NEJM special report note that there are still many questions that need to be answered regarding prenatal Zika infection — for example, if a pregnant woman becomes infected, what's her risk of giving birth to a baby with defects? It's also still unknown how many abnormalities could be caused by Zika, which is why focus on research and the development of a vaccine are crucial, the authors conclude.

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