A rapidly expanding outbreak of a rare form of Ebola is raising alarm across Central and East Africa, with the World Health Organization (WHO) warning that the risk remains “very high” in the Democratic Republic of the Congo (DRC) and “high” in neighbouring Uganda as infections continue to climb and spread across borders.

According to the WHO's latest rapid risk assessment released on June 6, the outbreak caused by Bundibugyo virus disease (BVD) has surged dramatically in just a few weeks. In the DRC, confirmed cases have increased from 63 to 515 and deaths from four to 91 – a case fatality rate of almost 18%. This is the biggest Bundibugyo Ebola outbreak ever recorded, and the virus is now spreading across 25 health zones in the provinces of Ituri, North Kivu, and South Kivu.

The outbreak was first detected in early May after reports of unexplained illnesses and deaths from a gold-mining region in Ituri Province. Genetic sequencing later confirmed that Bundibugyo virus, a rare strain of Ebola that has only previously caused two outbreaks, one in Uganda in 2007 and another in DRC in 2012, was present.

Unlike the more familiar Ebola virus species, Bundibugyo virus remains poorly understood. Scientists say there is currently no licensed vaccine and no approved antiviral treatment specifically designed for this strain. Patients rely largely on supportive care, such as fluids, oxygen, and treatment for complications, making early detection crucial.

The WHO report paints a troubling picture of an outbreak fuelled by delayed detection, conflict, population displacement and public mistrust. Investigators believe the virus may have been circulating unnoticed since March, allowing multiple chains of transmission to become established before authorities recognised the threat. Only about 30% of more than 5,000 identified contacts are currently being monitored because insecurity and population movement continue to hamper response efforts.

Healthcare workers are paying a particularly heavy price. At least 16 health workers in the DRC and five in Uganda have been infected, highlighting weaknesses in infection prevention systems. Scientists have long recognised that Ebola outbreaks can rapidly overwhelm fragile health services, especially in regions already battling diseases such as malaria, cholera and mpox.

Cross-border transmission has already been confirmed. Uganda has reported 19 cases, including two deaths, all linked to infections imported from the DRC or their contacts. A separate infected traveller also passed through the United Arab Emirates, prompting international contact tracing, although no onwards transmission has been detected there.

For ordinary families living in affected communities, the threat extends beyond infection. More than 26 million people in the DRC already face acute food insecurity, while conflict and displacement continue to disrupt access to healthcare. Public health experts warn that fear, misinformation and reluctance to seek treatment could be as dangerous as the virus itself if communities lose trust in response measures. The WHO reports that despite the sharp rise in cases, the global risk assessment remains low, with transmission still concentrated in the DRC and Uganda.

However, the agency has urged neighbouring countries to strengthen surveillance, border screening, laboratory capacity and community engagement to prevent further spread. The lesson from previous Ebola outbreaks is clear: outbreaks are easiest to stop if communities, healthcare workers and authorities act before transmission gains momentum.