Zika virus, which has been locally transmitted in 52 countries since 2007, has already been suspected of being linked to microcephaly (a birth defect that causes smaller heads and other problems) in babies who were exposed in the womb. But now, a first-of-its-kind study has shown that it may be linked to a scary syndrome in adults, too. The February 2016 study, which was published in the The Lancet, is small (it looked at 42 patients), but it's the strongest evidence so far to show a link between Zika and Guillain-Barré syndrome, a rare disorder that causes the body's immune system to attack the nervous system and can leave people temporarily paralyzed. Most people eventually recover, but Guillain-Barré can be fatal.
Researchers from the Pasteur Institute in Paris studied a Zika virus outbreak in French Polynesia from October 2013 to October 2014; cases of Guillain-Barré syndrome also spiked during that time. They found that 42 patients were diagnosed with Guillain-Barré, and all but one had antibodies in their system that killed the Zika virus. In a control group, only 56 percent of people had those antibodies.
88 percent of the Guillain-Barré patients had also experienced Zika-like symptoms, usually around six days before they noticed any neurological symptoms. Interestingly, the Guillain-Barré patients who had the Zika virus saw their symptoms get worse faster than typical Guillain-Barré patients — but they also recovered faster. None of the patients in the study died, but some needed help walking months after contracting the syndrome.
But experts want to reassure people that if they contract the Zika virus, that doesn't necessarily mean they'll suffer from paralysis. The risk is extremely low. Based on their numbers, the researchers estimated that 24 out of every 100,000 Zika patients in French Polynesia developed Guillain-Barré. According to the New York Times, doctors in countries with the Zika virus have also noticed upticks in Guillain-Barré patients, but they haven't confirmed whether the cases were caused by Zika.