The World Health Organization has warned that a rapidly spreading Ebola outbreak in eastern Democratic Republic of Congo could become the deadliest in the disease’s history. In a report published on August 13, the outbreak was said to have caused more than 4,300 infections and over 2,000 deaths, with health authorities struggling to keep pace with transmission.

The Congolese government formally declared the outbreak on May 15, although genetic analysis indicated that transmission began in February. The outbreak involves the rare Bundibugyo strain, for which no vaccine or treatment has yet been approved. WHO Director-General Tedros Adhanom Ghebreyesus said the current pace could surpass the death toll of the 2014-16 West African Ebola epidemic, which killed more than 11,000 people.

Remote terrain, continuing conflict near the borders with South Sudan, Uganda and Rwanda, weak infrastructure and limited resources are obstructing access to affected communities. Misinformation and strikes by unpaid health workers have also slowed response efforts. WHO official Abdirahman Mahamud said a moderate forecast projects a peak within six months, while a worse scenario could last nine to 12 months.