The battle against Ebola now underway in central Africa is like no other .

It is the first for which doctors have both a promising vaccine and treatments to offer. These medical innovations are experimental, but the vaccine seems to work well, the four new treatments have given preliminary hints of curative powers and a clinical trial of them began Monday.

It had seemed, with the help of these new tools, that the outbreak was headed for a quick end. Instead, with 419 cases and 240 deaths , it is now the second deadliest ever (although the 2014 West African one was orders of magnitude larger, with over 28,000 cases and 11,000 deaths).

Dr. Peter Salama, the W.H.O.’s emergency response chief, recently said he expected this outbreak to last at least another six months.

That’s because it is unique in another way: it’s the first to erupt in an area rived by gun battles. Doctors and other experts currently or formerly working in the region described a landscape that is not quite a war zone but in which shooting can break out almost anywhere for unknown reasons.