The mosquito-spread Zika virus linked to a spike in birth defects and neurological syndromes is a public health emergency of international concern, the World Health Organization declared Monday.
The declaration followed an emergency meeting in Geneva, in which health experts from around the world reviewed the data on the outbreak blazing through South and Central Americas. In some areas, infection with the Zika virus has been associated with a paralyzing neurological condition, known as Guillain-Barré syndrome, and microcephaly, in which babies are born with severely shrunken and deformed heads and brains.
In Brazil, which reported its first case of Zika last May, the virus has infected an estimated million people and been linked to a 20-fold increase in microcephaly cases. Since the outbreak began, health officials there have reported around 4,000 confirmed and suspected cases of microcephaly, compared to just 147 in 2014.