# Genomic Insights into Marburg Virus Strains from 2023 and 2025 Outbreaks in Kagera, Tanzania

## TL;DR

This study analyzes the genomic data of Marburg virus strains from two outbreaks in Tanzania and finds they are closely related, suggesting a single spillover event.

## Contribution

The study provides new genomic insights into MARV strains from recent outbreaks in Kagera, Tanzania, and their relationship to other outbreaks in East Africa.

## Key findings

- The MARV strains from the 2023 and 2025 outbreaks in Tanzania are closely related with >99.71% nucleotide identity.
- The strains clustered with MARV strains from outbreaks in Rwanda (2024) and Uganda (2014).
- The findings suggest a possible single spillover event followed by limited human-to-human transmission.

## Abstract

Marburg virus (MARV) is the primary cause of Marburg virus disease (MVD), a severe hemorrhagic fever with a high case-fatality rate. The first reported MVD outbreak in Tanzania occurred in 2023, followed by a second outbreak in 2025, both within the Kagera region. During those MVD outbreaks, 174 suspected cases were identified; of those, 10 were laboratory confirmed. After complete genome assembly and bioinformatic analyses, we found the MARV strains of the 2023 and 2025 outbreaks to be closely related and clustered with MARV strains that caused outbreaks in Rwanda (2024) and Uganda (2014). The sequences from both MVD outbreaks in Tanzania showed >99.71% nucleotide identity, suggesting a possible single spillover event followed by limited human-to-human virus transmission. Further ecologic studies are essential to identify potential spillover events, but our findings indicate that closely related MARV strains circulate in Kagera, Tanzania, posing a risk for future outbreak recurrence.