Genomic and transmission dynamics of the 2024 Marburg virus outbreak in Rwanda

The ongoing outbreak of Marburg virus disease in Rwanda marks the third largest historically, although it has shown the lowest fatality rate. Genomic analysis of samples from 18 cases identified a lineage with limited internal diversity, closely related to a 2014 Ugandan case. Our findings suggest that the Rwandan lineage diverged decades ago from a common ancestor shared with diversity sampled from bats in Uganda. Our genomic data reveal limited genetic variation, consistent with a single zoonotic transmission event and limited human-to-human transmission. Investigations including contact tracing, clinical assessments, sequencing and serology, linked the index case to a mining cave inhabited by Rousettus aegyptiacus. Serology tests identified three individuals seropositive for immunoglobulin G and immunoglobulin M, further supporting the zoonotic origin of the outbreak through human-animal interactions.