The World Health Organization says reports from several countries suggest that sexual transmission of the Zika virus is more common than previously thought.

After a meeting of its emergency committee on Tuesday, the U.N. health agency also said there is increasing evidence that a spike in disturbing birth defects is caused by Zika, which is mostly spread by mosquito bites.

Director-General Dr. Margaret Chan said "reports and investigations in several countries strongly suggest that sexual transmission of the virus is more common than previously assumed."

The agency last month said the outbreak in the Americas constitutes a global emergency.

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