WHO: Bundibugyo Ebola Outbreak in eastern DRC ‘evolving rapidly’ as cases spread into Uganda

The World Health Organization says the Ebola outbreak caused by the Bundibugyo virus in eastern Democratic Republic of the Congo is “evolving rapidly,” with many newer infections not yet tied to known chains of transmission — a warning that responders still do not have a clear view of how the virus is spreading. Separately, Africa CDC officials, not WHO, have described the outbreak as the fastest-growing Ebola outbreak ever based on its early pace of case growth.

The outbreak is centered in Ituri province in northeastern Congo, with cross-border cases in Uganda. Congo declared the outbreak on May 15, and WHO Director-General Tedros Adhanom Ghebreyesus declared it a Public Health Emergency of International Concern on May 17. In WHO’s most recent fully sourced snapshot, published July 3 and reflecting data through July 1, Congo had recorded 1,460 confirmed cases and 452 confirmed deaths. Uganda had 20 confirmed cases as of July 2, including two deaths, plus one probable death.

The concern is not only the scale of the outbreak but how unevenly it is being tracked. WHO said there is a “limited understanding of epidemiological links,” meaning many recent cases cannot be clearly connected to known patients or clusters. That makes containment harder because classic Ebola control measures — isolating patients, tracing contacts and monitoring them, and ensuring safe burials — depend on knowing who infected whom.

WHO reported 10,821 contacts under follow-up as of July 1, including 8,376 in Ituri and 2,445 in North Kivu. But follow-up rates were about 83.2% in Ituri and 81% in North Kivu, below ideal operational targets in many areas. Confirmed cases had been reported across 36 health zones by July 1 — 24 in Ituri, 11 in North Kivu and one in South Kivu — underscoring how widely the outbreak has spread across eastern Congo.

The toll on the health system is also significant. WHO reported 102 confirmed infections among health and care workers and 25 deaths among those workers. At the same time, WHO and its partners say the response has been hindered by insecurity and conflict, population movement and displacement, community resistance, reported attacks and arson involving treatment facilities, and some strikes or payment disputes among response workers.

Africa CDC’s description of the outbreak as the fastest-growing ever came from Wessam Mankoula, an Africa CDC official, who said in briefing remarks reported by news outlets: “This is the fastest growing Ebola outbreak ever, not only among the previous Bundibugyo outbreaks, but all the different viruses that are causing Ebola.” He compared 1,596 cases in the first six weeks of this outbreak with 994 cases in the first six weeks of the 2013-16 West Africa epidemic.

A major challenge is that there are no licensed vaccines or approved treatments specifically for Bundibugyo virus disease. Existing approved Ebola countermeasures target Zaire ebolavirus, the more common species behind several previous outbreaks, not Bundibugyo. On July 2, WHO announced the start of the randomized PARTNERS trial in Congo to test possible treatments for Bundibugyo virus disease, including MBP134 and remdesivir alone and in combination. “Even without approved therapeutics, people are recovering from this disease, but of course, we could save many more lives with safe and effective therapeutics in our toolkit,” Tedros said in WHO’s announcement.

Bundibugyo virus is a less common Ebola species first identified in Uganda in 2007. This is Congo’s 17th recorded Ebola outbreak since 1976, but the setting matters: conflict, displacement and cross-border movement in the east make outbreaks harder to contain than in more stable conditions. WHO’s risk assessment reflects that balance: very high nationally, high regionally and low globally.