The WHO, which declared the accelerating outbreak a global emergency on Thursday, voiced fresh concern that the virus could spread undetected in a country with a weak health system.

There is a “huge reason to keep official border crossings open” to avoid people entering irregularly and going unchecked for symptoms, WHO spokesman Christian Lindmeier told a Geneva briefing. “If travel restrictions would be imposed we hope they are as short-lived as possible to try to continue the normal flow of life,” he added.

REUTERS