The Ebola outbreak in the Democratic Republic of Congo has crossed a grim milestone. More than 4,000 people have died out of about 8,300 confirmed cases, health authorities said.

The outbreak was declared on May 15 in the Bundibugyo region of eastern Congo. It is being described as one of the fastest-growing Ebola outbreaks on record.

Response teams face a difficult situation on the ground. Violence around displacement camps is hampering efforts to reach patients and trace contacts, officials said.

Ebola spreads through contact with body fluids. Early care improves survival chances, and vaccines exist for some strains.

Health workers continue to appeal for safe access to affected areas. The World Health Organization has been supporting surveillance and treatment centres in the region.

The outbreak is a reminder of how conflict can turn a disease emergency into a larger crisis.

Vaccination campaigns continue in the areas that health teams can safely reach.