Emergence of a Bundibugyo virus variant in the 2026 outbreak in the Democratic Republic of the Congo and Uganda

Abstract

In May 2026, an outbreak of Ebola disease caused by Bundibugyo virus (BDBV, species Orthoebolavirus bundibugyoense) was declared in the Democratic Republic of the Congo (DRC), with cases originating from the DRC and locally transmitted cases reported in Uganda. Bundibugyo virus disease (BVD) outbreaks were previously recorded in 2007–2008 in Bundibugyo District, Uganda, and in 2012 in Isiro, DRC. Here we generated 22 genomes from samples obtained from individuals with BVD in the DRC and Uganda. These genomes form a well-supported phylogenetic cluster separate from BDBV variants associated with the 2007 and 2012 outbreaks, together with evidence for sustained human transmission. This is consistent with the emergence of a new zoonotic spillover event rather than resurgence of previously reported variants. Alongside ongoing efforts to strengthen surveillance systems and community engagement, establish Ebola treatment centers and develop targeted medical countermeasures, our report advocates for specifically increasing decentralized laboratory-diagnostics capacity, with pan-Orthoebolavirus assays, including genomic sequencing capacity, to limit further outbreak expansion and enable timely detection and control of future outbreaks.