Zika virus: Up to four million people could be infected - WHO

Three to four million people could be infected with Zika virus in the Americas this year, the World Health Organization predicts.

Most will not develop symptoms, but the infection has been linked to brain defects in babies.

Meanwhile the US says it hopes to start vaccine trials in people by the end of the year.

WHO director general Dr Margaret Chan said Zika had gone "from a mild threat to one of alarming proportions".

She has set up a Zika "emergency team" after the "explosive" spread of the virus.

It will meet on Monday to decide whether Zika should be treated as a global emergency.

The last time an international emergency was declared was for the Ebola outbreak in West Africa which has killed more than 11,000 people.