Bundibugyo virus (BDBV), a distinct ebolavirus species, was first identified during a 2007 Ebola virus disease (EBOD) outbreak in Bundibugyo District, Uganda, where it caused approximately 100 probable or confirmed cases and about 40 deaths.
In 2012, BDBV re-emerged in the Isiro Health Region, Democratic Republic of the Congo (DRC), about 400 km from Bundibugyo. The outbreak, officially recognized in August and declared over in November 2012, resulted in 38 laboratory-confirmed cases and 13 deaths (34% case fatality), with higher lethality estimates when suspected and probable cases are included. Previously, only five complete BDBV genomes, one from 2007 and four from 2012 were available. The presented work adds 11 complete genomes from the 2012 outbreak: six directly from patient sera and five after cell-culture passage. Analyses identified 12 segregating sites among viruses sampled over a 104-day period and revealed at least two co-circulating BDBV lineages. A central cluster was anchored around an early case with onset June 28th 2012, presumed ancestral to most subsequent infections. However, two cases fell outside this cluster and showed distinct SNP patterns. Analyses challenged earlier assertions that a single September 2012 spillover seeded the outbreak. The genomic data were more consistent with either an earlier, unrecognized introduction well before official outbreak declaration or multiple independent zoonotic spillovers from an unidentified reservoir, or both. Slow evolutionary rates and temporal gaps between genetically similar viruses also raise the possibility of persistent, asymptomatic infection with later reintroduction into humans.
The findings underscore the need for improved genomic surveillance, better field epidemiology, and continued efforts to identify BDBV’s natural reservoir and the mechanisms of spillover.
Original article:
- Hulseberg CE, Kumar R, Di Paola N, Larson P, Nagle ER, Richardson J, Hanson J, Wauquier N, Fair JN, Makuwa M, Mulembakani P, Muyembe-Tamfum JJ, Schoepp RJ, Sanchez-Lockhart M, Palacios GF, Kuhn JH, Kugelman JR. Molecular analysis of the 2012 Bundibugyo virus disease outbreak. Cell Rep Med. 2021 Jul 27;2(8):100351. https://doi.org/10.1016/j.xcrm.2021.100351