Cross-border transmission corridors and diffusion velocities of Ebola-virus in in the Great-lakes basin: A 1976-2025 multilayered phylogeographic analysis.
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Background Ebola disease (EBOD) outbreaks are recurrent and highly lethal in the Great-Lakes basin, yet regional-scale evolutionary reconstructions are lacking. Objectives To locate the long-term reservoir, quantify cross-border transmission corridors and measure diffusion velocities of EBOD outbreaks across central Africa during 1976–2025. Methods We curated 110 complete Ebola virus genomes from GenBank and BV-BRC, aligned them with MAFFT, and inferred a time-scaled phylogeny in BEAST v1.10.5. A dual-layer Bayesian framework coupled (i) a discrete Bayesian stochastic-search variable-selection (BSSVS) model for country-to-country migration with (ii) a continuous Cauchy relaxed random walk (RRW) for kilometre-scale movement. Posterior trees (300 million states; ESS > 200) were visualised in EvoLaps 2.42; Markov-jump counts, Bayes factors (BF) and branch velocities were extracted. Results Our dual-layer reconstruction shows that Ebola circulation is firmly rooted in north-eastern DRC: 80% of the root posterior density clusters within a 150 km radius of the Yambuku-Ituri-Likati forests axis, identifying this block of lowland rainforest as a persistent enzootic cradle. From that focus, diffusion unfolded in three distinct temporal phases initially as short-range local spread (1976–1987), then as a westward, Congo/Kasai river-mediated wave (1994–2007), and, since 2007, as an east-south-east advance toward Lakes Albert and Edward that underpins recent Ugandan outbreaks. Cross-border movement is dominated by the Lake-Albert corridor: Bayes factors of 32.1 for DRC to Uganda and 26.4 for Uganda to DRC, together with a median 13.4 Markov-jump events, account for three-quarters of all international transitions in the posterior; by contrast, only a single westward leap reaches the Gabon/Cameroon littoral (BF = 6.4). Continuous-model vectors yield a mean radial expansion of 7.9 km year⁻¹ (95% HPD: 5.4–10.6 km year⁻¹), yet the distribution’s heavy tail reveals rare founder events that cover more than 150 km in a single transmission chain. Conclusions A single Yambuku-Ituri-Likati forest axis hearth has seeded all documented EBOD outbreaks, with transmission funnelling chiefly through informal Lake-Albert crossings. Sentinel surveillance in this area, corridor-focused border health teams, and pre-emptive vaccine positioning along the Ituri-Lakes corridor could blunt future outbreaks.
