The World Health Organization said Friday that it will know in a matter of weeks whether the Zika virus causes microcephaly and the severe neurological disorder Guillain-Barre syndrome. 

The UN health agency's deputy director for health systems and innovation, Marie-Paule Kieny, said it would likely take four to eight weeks to establish whether there is a causal relationship between the conditions. 

While most people infected with Zika have only mild symptoms, the virus is strongly suspected of being linked with microcephaly, which can cause babies to be born with abnormally small heads and brains, and Guillain-Barre, a disorder that can cause paralysis or even death.