Scientists discover evidence of Zika link to neurological disorder
Guillain-Barré syndrome is a rare response to infection, resulting in the immune system attacking peripheral nerves
New research gives the first evidence that Zika virus might cause a severe neurological disorder called Guillain-Barré syndrome.
The study was carried out using blood samples from 42 patients who became ill in a previous outbreak.
The Lancet authors say they developed the neurological problems around six days after Zika infection.
Leading scientists described the study as "compelling".
Zika was declared a public health emergency of international concern by the World Health Organisation (WHO) in early February.
The virus, which is transmitted by mosquitoes, has caused alarm in central and south America because of its suspected links to under-developed brains in babies - a condition called microcephaly.
But experts have also questioned whether Zika might be linked to another medical condition as well.
Guillain-Barré syndrome leads to muscle weakness and, in severe cases, breathing problems requiring intensive care.