The latest Ebola outbreak has become the second worst in African history.
Over 425 people have been infected in the North Kivu region of the Democratic Republic of Congo.
So far, more than half of those have died.
The mortality rate for Ebola high at 63 percent, and this time the virus is proving even harder to contain.
Most of the outbreaks began in deeply isolated areas in sub-Saharan Africa.
Not this one.
It began in August among dense and very mobile local populations.
Health workers are struggling to establish an effective vaccination program, with ongoing rebel militia violence making the task harder.
Reuters' Giulia Paravicini is in the DRC.
SOUNDBITE (English) GIULIA PARAVICINI, DEMOCRATIC REPUBLIC OF CONGO CORRESPONDENT, REUTERS, SAYING: "Containment of the current outbreak is particularly difficult since response teams are being stopped in their daily job by increased insecurity within the city of Beni, and also by community resistance.
Vaccinations are available, but often, because of the insecurity, teams have to stop the vaccinations and also surveillance and tracing contacts of patients, and transferring the patients to treatment centers.
This obviously slows down the response, and favors the spread of the disease." Since its initial discovery in 1976, Ebola's posed most risk to this central swathe of Africa: from Guinea in the west to Uganda and the Democratic Republic of Congo in the east.
The red dots illustrate the locations of previous outbreaks.
The biggest so far was between 2014 and 2016 in Guinea, Liberia and Sierra Leone in which more than 11,000 people died.
The current outbreak is centered on North Kivu in the DRC - the 10th the country has experienced - and now bigger than one in Uganda in 2000.
Health workers are not only hampered by gunfire.
They often face resistance from the Congolese who accuse medics of spreading Ebola with their vaccination needles, or believe it does not exist at all.
Those who do seek medical help often find themselves in unsanitary medical facilities where the virus spreads.
Delays to blood tests, and the isolation and safe burial of victims also do little to prevent the spread of Ebola.