The Bundibugyo ebolavirus outbreak in the Democratic Republic of the Congo has reached 2,181 confirmed cases and 864 deaths, pushing the case fatality rate to 39.6 per cent, according to government figures released on 18 July. The World Health Organization, which declared the outbreak a public health emergency of international concern in May, reports that sustained transmission is concentrated in the eastern province of Ituri, where the majority of new infections are detected outside existing contact lists and roughly two-thirds of fatalities occur in communities rather than in treatment centres. Uganda, which recorded 20 cases, discharged its last patient on 16 July and has begun a 42-day enhanced surveillance countdown required before the outbreak can be declared over there.

Virologists studying the Bundibugyo strain have identified a clinical feature that is reshaping the response: a slower disease progression that allows patients to remain ambulatory and infectious for extended periods. Corri Levine, a virologist who examined the strain, describes it as a “walking” presentation in which early symptoms are mild enough that individuals do not feel incapacitated and continue to move within their communities. This longer window of mobility delays isolation and means that by the time patients seek care, viral loads are often already high and multiple organ failure is imminent. Geneticist Pardis Sabeti of the Broad Institute of MIT and Harvard warns that prolonged circulation of the virus increases the probability of genetic changes with unpredictable consequences. No licensed vaccine or treatment exists for the Bundibugyo strain, though Russia has developed a candidate vaccine that has yet to enter clinical trials.

Response operations are severely constrained by the security environment in eastern DRC. Armed clashes limit access to affected populations, and a treatment centre in Bunia was attacked the day before the WHO director-general’s latest statement. Health workers also face resistance from communities angered by restrictions on traditional burial practices and by food shortages that drive patients to leave isolation units in search of sustenance. The WHO and Africa CDC are supporting the Congolese health ministry with surveillance, laboratory capacity, and community engagement, but officials in Geneva stress that a purely medical response cannot contain the outbreak without parallel political efforts to secure humanitarian access and protect frontline personnel.

The immediate metric to watch is Uganda’s 42-day surveillance period, which if completed without new cases would confirm containment across the border. Inside DRC, the trajectory hinges on whether a temporary ceasefire or other political arrangement can create the conditions for effective contact tracing and early treatment. Without such access, the outbreak is likely to continue generating cases outside known transmission chains, sustaining what is already the third-largest Ebola event in the country’s history.