DR Congo Ebola risk high regionally, low worldwide: WHO

The deadly Ebola outbreak raging in central Africa probably began several months ago, the World Health Organization said Wednesday, deeming the risk high in the region but low worldwide.

WHO experts said that investigations were under way into the origins of the outbreak, which was declared in eastern Democratic Republic of Congo last Friday, but the suspicion was that the contagious haemorrhagic fever had been spreading under the radar for some time.

"Given the scale, we are thinking that it has started probably a couple of months ago," Anais Legand, WHO technical officer on viral haemorrhagic fevers, told reporters in Geneva.

Ebola has killed more than 15,000 people in Africa in the past half-century, and the UN health agency declared the latest surge an international health emergency.

The 17th Ebola outbreak to hit the DRC is already suspected of having caused 139 deaths from around 600 probable cases.

"We expect those numbers to keep increasing, given the amount of time the virus was circulating before the outbreak was detected," WHO chief Tedros Adhanom Ghebreyesus told reporters.

The WHO has highlighted the complexity of detecting and responding to the outbreak, which has been spreading in hard-to-reach areas of the DRC's conflict-torn Ituri province.

Complicating things further, the less common Bundibugyo species behind the outbreak does not show up on tests for the more common Zaire strain of Ebola.