Contact tracing is improving. Treatments may be months away. Here’s what could determine whether a fast-expanding outbreak can be slowed down.

Health workers have warned that the outbreak, already one of the worst in decades, could take as long as a year to contain if infection rates do not flatten.

The vaccine development process and coordination between health organizations have improved since a devastating 2014-2016 outbreak.

China is well positioned to help stop the deadly virus, and could move into a gap left by U.S. retreat.

Aid agencies are racing to help health workers in the Democratic Republic of Congo. The virus is known to have killed at least 140 people, but the true toll may be far higher.

Mining has been the lifeblood of this remote Congolese hill town for decades. Now, it is fueling the spread of a devastating virus.

Dr. Tedros Adhanom Ghebreyesus, the director general of the World Health Organization, told The New York Times on a flight to the Democratic Republic of Congo that swift international support was necessary to contain the Ebola virus, which is spreading rapidly there.

A remote gold mining town is under siege, as medical workers struggle to beat back a surge of deaths and infections.

Uganda said that flights to and from the Democratic Republic of Congo would be temporarily suspended, as the outbreak appeared to spread to a rebel-controlled province in Congo.

An Air France plane was sent to Montreal because a passenger from the Democratic Republic of Congo was on board. The U.S. has closed its borders to recent visitors to the African country.

To some Africans, the claim that the continent’s largest health agency had already bungled its response scratched a familiar wound.