Scientists may have found the first compelling evidence that the Zika virus causes a rare yet dangerous neurological disorder than can paralyze and kill.
The new study linked an outbreak of the mosquito-bred infection in French Polynesia two years ago to Guillain-Barré syndrome (GBS), which wreaks havoc on the immunity and the nervous system.
Researchers analyzed blood samples coming from 42 individuals diagnosed with GBS during a major episode of the Zika virus in the French Polynesia islands from October 2013 to April 2014, before the virus swept through Latin America last year.
Of the GBS patients investigated, 88 percent reported signs of Zika about six days before signs of the neurological condition started to manifest.
According to lead author Arnaud Fontanet, a professor from Institut Pasteur in France, their research is the first to offer proof of the Zika virus-GBS link.
"Most of the patients with GBS reported they had experienced symptoms of Zika virus infection on average six days before any neurological symptoms, and all carried Zika virus antibodies," he reiterates.
Data suggested that 24 out of 100,000 individuals infected with Zika would likely develop GBS, which affects only around one to two out of 100,000 in Europe and North America.
Fontanet said that while it is still undetermined whether the attack rates will be as high in Latin American regions as in the Pacific, an increase in GBS cases among those who have been infected with the Zika virus might have to be anticipated in the months to come.
These results are a push for Zika virus to be incorporated in the list of pathogenic viruses prone to causing GBS, he added.
In a comment accompanying the research, University of Western Australia Professor David W. Smith said that "a little caution" needs to be taken since data on the association remains scarce and it is yet to be determined if the current Zika virus is identical to those of previous outbreaks.
"Suffice to say Zika virus can be added to our list of viruses that can cause Guillain-Barré syndrome," he writes.
The symptoms of Guillain-Barré syndrome — which is not contagious, and whose exact roots remain mysterious — develop within two to four weeks. They generally include muscle pain and weakness present in the arms and legs.
In severe cases, GBS can result in paralysis of the muscles, which affects one's swallowing, breathing and speech.
Wellcome Trust director Dr. Jeremy Farrar said the magnitude of the health crisis taking place in Latin America, where investigation is underway to determine if there is a link between cases of Zika virus infection in pregnant women and babies born with abnormally small heads, a condition called microcephaly, has taken everyone by surprise.
"We should be prepared for further unforeseen complications of Zika virus infection to emerge in the coming weeks and months," he said.
The findings were published Monday in the journal Lancet.
