Outbreak of the Zika virus is a global public health emergency, the World Health Organisation warned today
The alert puts the mosquito-borne disease in the same category as Ebola, which killed 11,000 people in West Africa
Experts predict there could be four million cases of the virus, which has spread to 23 countries, this year
WHO director general Dr Margaret Chan called it an 'extraordinary event' and called for an international response
There is no cure or vaccination for the virus, which is linked to babies being born with abnormally small heads