For the first time, researchers have shown that the Zika virus can cause Guillain-Barre syndrome, a rare condition in which the immune system attacks nerve cells and causes paralysis.
Five Latin American countries with Zika epidemics — Brazil, El Salvador, Venezuela, Colombia and Suriname — have reported increases in Guillain-Barre syndrome. Until now, however, doctors didn’t have scientific evidence showing the virus actually triggers the condition.
The new evidence comes from a study published Monday in The Lancet, in which researchers analyzed 42 cases of Guillain-Barre syndrome that were diagnosed during a Zika outbreak in French Polynesia from 2013 to 2014. Scientists estimate about 66% of the territory’s residents were infected.
In the study, doctors compared patients with Guillain-Barre to those hospitalized for other reasons. All 42 of the Guillain-Barre patients had antibodies designed to neutralize Zika’s effects on the body, compared with about half of control patients.
About 88% of the Guillain-Barre patients had experienced Zika-like symptoms — such as fever, rash and joint pain — about six days before developing paralysis, according to the study.
That’s a significant detail, according to an accompanying commentary from researchers David Smith at the University of Western Australia and John Mackenzieof Curtin University, also in Australia.
Only about 20% of patients with Zika infections develop symptoms, according to theCenters for Disease Control and Prevention. The study’s results suggest that people who are infected with Zika but don’t develop symptoms might be at lower risk from complications, Smith and Mackenzie wrote.
Guillain-Barre typically begins with weakness in the legs, then moves up the body. One in four patients end up on a ventilator because the condition paralyzes the muscles they need to breathe. Although some patients recover fully, 20% are left with a significant disability and about 5% die, Smith and Mackenzie wrote.
About 38% of Guillain-Barre patients in French Polynesia needed intensive care, usually because patients needed breathing machines, according to the study.
Yet patients in this outbreak recovered more quickly than usual; about half were able to walk without help three months later, according to the study.
