Airline crew on leave after flight with infected nurse

US President Barack Obama has authorised the Pentagon to call up reserve and National Guard troops if they are needed to assist in the US response to the ebola outbreak in Africa.

The US has already committed to sending up to 4,000 military personnel to West Africa to provide logistics and help build treatment units to confront the rapidly spreading and deadly virus.

Obama signed an executive order that permits the Pentagon to use the reservists and Guard troops.