The Democratic Republic of the Congo's Ebola outbreak has crossed a threshold public-health officials had hoped to avoid. "A total of 4,381 Ebola cases across five provinces of the DRC have been confirmed as of Tuesday, including 2,011 deaths," Al Jazeera reported on August 11 [1].
That scale puts the outbreak in grim company. It is the fastest-growing Ebola outbreak on record in the country and second in size only to the West African outbreak of 2014 to 2016, during which 11,310 people died [1]. The DRC has weathered repeated Ebola flare-ups over the decades; none has climbed this fast.
The reason the usual playbook is not working sits in the virus itself. The outbreak is driven by the rare Bundibugyo strain, and, as Al Jazeera notes, "there is currently no approved treatment or vaccine" for it [1]. The licensed Ebola vaccine and the antibody therapies that helped bend the curve in earlier epidemics were developed against the Zaire strain; they are not cleared for Bundibugyo. Responders are therefore working the outbreak with isolation, contact tracing, and supportive care rather than the pharmaceutical tools that shortened past outbreaks.
The outbreak was officially declared in the DRC and neighbouring Uganda on May 15 [1]. Five provinces are now reporting confirmed cases, a geographic spread that complicates the contact tracing on which containment depends.
The figure to hold onto is the gap between 4,381 cases and 2,011 deaths: a case-fatality rate near half, in a country where the medical countermeasures that worked before were built for a different strain of the same virus.
