The ongoing outbreak of Marburg virus disease (MVD) in Rwanda marks the third largest historically, though it has exhibited the lowest fatality rate. Genomic analysis has identified a lineage with limited internal diversity most closely related to a genome sequence from a sporadic case sampled in 2014 in Uganda, though the lineages have diverged from a common ancestor that was circulating for decades in the animal reservoir. Notably, the data also provide evidence that the outbreak resulted from a single zoonotic transmission event with limited human-to-human transmission, rather than multiple independent zoonotic transmission events. The Rwandan MVD outbreak prompted a thorough investigation that included contact tracing, clinical assessment, travel history, sequencing, and serology testing, to trace the virus's origin. Results of investigations linked the index case to a mining cave inhabited by Rousettus aegyptiacus (the Egyptian fruit bat), where three individuals tested seropositive for IgG and IgM, further supporting the zoonotic origin of the outbreak through human-animal interactions.

The authors have declared no competing interest.

Government of Rwanda and Development Partners.

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