Kagera, United Republic of Tanzania · 20 January 2025
Tanzania's Ministry of Health declared an outbreak of Marburg virus disease (MVD) on 20 January 2025, centered in Biharamulo district in the Kagera region. It was the country's second MVD outbreak in three years — both occurring in the same border region near Rwanda and Uganda. The outbreak was declared over on 13 March 2025 after two consecutive incubation periods (42 days) passed without a new confirmed case.
All 10 reported cases — two confirmed and eight probable — resulted in death, yielding a case fatality ratio of 100%. Eight of the victims died before the outbreak was even confirmed, their cases classified retrospectively as probable.
Tracing the Outbreak's Origins
The first identified case was an adult female whose symptoms began on 9 December 2024 and who died on 16 December 2024 — over a month before the outbreak was officially declared. The last confirmed case died on 28 January 2025 and received a safe and dignified burial in accordance with WHO protocols. No new confirmed or probable cases were reported after that burial.
All 10 cases were reported from Biharamulo district. The source of the outbreak remained unknown, with research activities planned to investigate the zoonotic origin. Marburg virus is carried by Rousettus fruit bats, and human infection typically occurs after prolonged exposure to mines or caves inhabited by bat colonies.
A Region Under Pressure
The Kagera region's location at the border with Rwanda and Uganda made cross-border coordination critical. Tanzania convened meetings with health authorities from both neighbouring countries. Travellers departing from Kagera Region were screened at key points of entry and exit, including Bukoba airport.
This outbreak followed closely on the heels of a Marburg outbreak in Rwanda that ran from September to December 2024 — the first ever reported in that country. The geographic clustering of filovirus outbreaks in the Great Lakes region has raised questions about ecological drivers, including potential changes in bat-human interaction patterns.
Response Architecture
Tanzania's response was guided by a national response plan developed by the Ministry of Health, with a National Incident Management System and national task force activated. At the sub-national level, daily coordination meetings were held in Kagera Region.
Key operational elements included:
- Rapid response: A national rapid response team was deployed to Kagera with technical and operational support from WHO and partners.
- Laboratory: A mobile laboratory deployed in Kabyaile supported rapid testing of suspected cases. Samples were referred to the National Public Health Laboratory in Dar es Salaam for additional testing.
- Treatment: The Marburg Treatment Unit was upgraded with enhanced triage, patient wards, and donning and doffing areas.
- Community engagement: Public awareness campaigns included door-to-door outreach by community health workers and public announcements in high-risk areas. Health and care worker sensitisation sessions on infection prevention and control were conducted across Kagera and other regions.
- WHO support: WHO deployed experts in emergency management, clinical management, health logistics, and infection prevention and control. Four viral haemorrhagic fever (VHF) kits were procured and delivered to Kagera.
No Vaccine, No Treatment
There is currently no approved treatment or vaccine for Marburg virus disease. Several candidate vaccines and therapeutics are under investigation. WHO has convened a Technical Advisory Group that evaluated four candidate Marburg vaccines, and a Marburg vaccine landscape has been published to guide research priorities.
The disease is clinically similar to Ebola disease. Illness begins abruptly with high fever, severe headache, and severe malaise. Severe watery diarrhoea, abdominal pain, cramping, nausea, and vomiting can begin on the third day. Haemorrhagic manifestations may appear between five and seven days from symptom onset, and fatal cases usually involve bleeding from multiple areas of the body. In fatal cases, death occurs most often between eight and nine days after symptom onset, typically preceded by severe blood loss and shock.
The Broader Filovirus Picture
Eighteen outbreaks of MVD have been reported globally to date. Countries in the WHO African Region that have reported outbreaks include Angola, the Democratic Republic of the Congo, Equatorial Guinea, Ghana, Guinea, Kenya, South Africa, and Uganda — in addition to Tanzania and the recent Rwanda outbreak.
Lessons for the Region
The speed of containment — 53 days from declaration to resolution — demonstrated the value of prior outbreak experience. Tanzania's first MVD outbreak in 2023, also in Kagera, established surveillance and response infrastructure that could be rapidly reactivated. The deployment of a mobile laboratory, the upgrading of treatment units, and the activation of cross-border coordination mechanisms all reflected institutional memory from the previous event.
Nevertheless, the 100% fatality ratio and the fact that eight cases were only identified after death underscore the persistent challenge of community awareness and early health-seeking behaviour. WHO's post-outbreak guidance emphasised sustaining early detection capabilities, maintaining the ability to respond quickly, and continuing risk communication and community engagement — not as post-crisis formalities, but as permanent investments in a region where filovirus spillover is an ongoing ecological reality.
Sources:
- WHO Disease Outbreak News, Marburg virus disease – United Republic of Tanzania, 13 March 2025.
- WHO African Region, Tanzania confirms outbreak of Marburg virus disease.
- WHO Factsheet, Marburg virus disease.
- WHO Technical Advisory Group – candidate vaccine prioritization, Marburg vaccines.
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Institutional Research Desk · Foresight Institute of Research and Translation
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