On any given morning in Mongbwalu, dozens of men and women descend into hand-dug pits in the ochre hills of Ituri province, their bodies pressed together in the narrow shafts, their hands cracking rocks for traces of gold. It is precisely the kind of close, sweating contact that the Bundibugyo strain of Ebola — for which no vaccine or approved treatment yet exists — exploits most efficiently. Since the outbreak was officially declared on 15 May, more than 1,000 cases have been recorded across the Democratic Republic of Congo, with at least 250 deaths confirmed nationally. In Mongbwalu alone, 209 infections and 89 fatalities have been reported, though health officials acknowledge that the true scale of the crisis is almost certainly larger than official figures suggest.

What makes this outbreak particularly difficult to contain is the collision between biology and economic reality. Many of the miners working the artisanal claims come from neighbouring provinces or from Uganda across the border, drawn by the possibility of earning a few hundred dollars a week. That constant movement of people across porous borders has accelerated transmission in a region where public institutions are already weakened by years of armed conflict. "They talk to us about preventive measures, but it is hard to follow them because our work forces us to be in contact with each other," said miner Justin Uketi, articulating a dilemma that no public-health poster has yet solved.

Distrust of formal medicine compounds the problem.