The arrival of Zika virus in Brazil doubled the rate of birth defects involving the nervous system, including microcephaly, researchers reported Wednesday.
Rates of Guillain-Barré syndrome — a rare, paralyzing side-effect of some infections — nearly tripled, the researchers said. And rates of other inflammatory conditions such as encephalitis doubled in the northeastern part of Brazil that was hardest hit by Zika, NBC News reported.
Separately, the World Health Organization tweaked its statement on Zika and the rise in rates of birth defects and Guillain-Barré syndrome, saying the virus is the "most likely explanation" for both.
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"Beginning in mid-2014, we observed an unprecedented and significant rise in the hospitalization rate for congenital malformations of the nervous system, Guillain-Barré syndrome, encephalitis, myelitis, and encephalomyelitis," Brazil's Oswaldo Cruz Foundation explained in its report, which was published in the Center for Disease Control and Prevention journal Emerging Infectious Diseases.