The World Health Organization says 80% of new Ebola cases in eastern Congo are now emerging from unknown chains of transmission, a sign the outbreak is outpacing the response despite expanded containment efforts. As of this week, at least 1,926 people have been infected and 702 have died from the rare Bundibugyo strain of the virus across three provinces since the outbreak was officially declared on May 15.

The Africa Centres for Disease Control has called it the fastest-growing Ebola outbreak on the continent. There is no approved treatment or vaccine specifically for this viral strain, and many of the newly reported deaths are people who died in their communities without ever reaching a health facility or receiving care.

Health officials say a funding gap, attacks on health centers, an ongoing armed conflict in eastern Congo, and deep mistrust among local communities have all hampered the response. Congolese authorities and WHO teams are racing to expand contact tracing and community engagement as the case count continues to climb.