Why DRC's Ebola virus outbreak is likely to become the worst in history

WHO director-general Tedros Adhanom Ghebreyesus says many of the deaths occurring in the Democratic Republic of the Congo are happening outside of known transmission chains, meaning the outbreak is a long way from being brought under control.

Ashanom Ghebreyesus - director general of the World Health Organisation (WHO) - has warned the outbreak is "already the second-biggest Ebola epidemic on record"

DRC has recorded 4,449 confirmed cases and 2,061 deaths across five provinces and 53 health zones.

Talks are underway between the Democratic Republic of the Congo and the WHO to expedite the start of a multi-armed Phase 3 clinical trial of Ebola vaccines.