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Situation at a glance
Since the declaration of the Marburg Virus Disease (MVD) outbreak on 20 January 2025 in the United Republic of Tanzania, one additional confirmed death was reported by the Ministry of Health from the epicentre of the outbreak in Biharamulo district in Kagera region.
As of 10 February 2025, a cumulative of two confirmed and eight probable cases were reported by the Ministry of Health.
All 10 cases have died, including eight who died before the confirmation of the outbreak.
As of 10 February 2025, all 281 contacts that were listed and under monitoring have completed the 21-day follow-up.
The Ministry of Health developed a national response plan to guide activities. Additionally, a national rapid response team was deployed to the affected region to enhance outbreak investigation and response, with technical and operational support from WHO and health partners.
Description of the situation
Since the previous Disease Outbreak News on this outbreak was published on 14 January 2025, two confirmed cases have been reported, and efforts are ongoing to ascertain the source of infection.
As of 10 February 2025, a cumulative of 10 cases have been reported including two confirmed and eight probable cases. All cases resulted in death, including eight who died before the confirmation of the outbreak.
The two cases confirmed since the outbreak declaration died while in isolation at a designated MVD treatment centre.
On 28 January, a safe and dignified burial was performed for the last confirmed case. No new confirmed or probable cases have been reported following this burial.
The presumptive index case, an adult female, had symptom onset on 9 December and died on 16 December 2024.
All 10 cases were reported from Biharamulo district in Kagera region; the median age of cases was 30 years (range: 1 to 75 years) and the majority of cases (70%, 7) were females.
Cumulatively, 90 suspected cases were reported between 20 January and 10 February, all of which tested negative for MVD.
As of 10 February 2025, all 281 contacts that were listed have completed 21 days of follow-up.
The first MVD outbreak in Tanzania was reported in March 2023 in Bukoba district in Kagera region, and zoonotic reservoirs, such as fruit bats, remain endemic to the area. The outbreak in March 2023 lasted for nearly two months with nine cases including six deaths.
Epidemiology
MVD is a highly virulent disease that can cause severe disease and is clinically similar to Ebola disease (EBOD).
EBOD and MVD are caused by orthoebolaviruses and orthomarburgviruses respectively; both are members of the Filoviridae family (filovirus).
People become infected after prolonged exposure to mines or caves inhabited by Rousettus fruit bat colonies, a type of fruit bat, that can carry the Marburg virus.
Marburg virus then spreads between people via direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids.
Health workers have previously been infected while treating patients with suspected or confirmed MVD.
Burial ceremonies that involve direct contact with the body of the deceased can also contribute to the transmission of Marburg virus.
The incubation period varies from two to 21 days. Illness caused by Marburg virus begins abruptly, with high fever, severe headache and severe malaise. Severe watery diarrhoea, abdominal pain and cramping, nausea and vomiting can begin on the third day. Although not all cases present with haemorrhagic signs, severe haemorrhagic manifestations may appear between five and seven days from symptoms onset, and fatal cases usually have some form of bleeding, often from multiple areas of the body. In fatal cases, death occurs most often between eight and nine days after symptom onset, usually preceded by severe blood loss and shock.
There is currently no approved treatment or vaccine for MVD. Some candidate vaccines and therapeutics are currently under investigation.
Eighteen outbreaks of MVD have previously been reported globally. The most recent outbreak was reported from Rwanda between September and December 2024. Additional countries that previously reported outbreaks of MVD in the African Region include Angola, the Democratic Republic of the Congo, Equatorial Guinea, Ghana, Guinea, Kenya, South Africa, the United Republic of Tanzania and Uganda.
Public health response
The Ministry of Health developed a national response plan to guide response activities.
A National Incident Management System was activated to coordinate the response to the event and a national task force was activated, and meetings are held weekly. At the sub-national level, regular coordination meetings are being held in Kagera Region.
A national rapid response team was deployed to the affected region to enhance outbreak investigation and response, with technical and operational support from WHO and health partners.
WHO has deployed experts to support the MoH with partner coordination and other response activities in different pillars.
Surveillance activities continue with active case finding and contact tracing across affected areas.
The mobile laboratory deployed in Kabaile continues to support the testing of suspect cases for rapid turnaround time, and samples are referred to the central public health laboratory in Dar es Salaam for additional tests. Additionally, genomic sequencing was conducted on the two positive samples.
Screening of travellers departing from Kagera Region continues at key points of entry and exit, including Bukoba airport.
Healthcare worker sensitization sessions on infection prevention and control are ongoing across Kagera and other regions.
The Marburg Treatment Unit has been upgraded with enhanced triage, patient wards, and donning and doffing areas. Public awareness campaigns, including health education, door-to-door outreach by community health workers, and public announcements in high-risk areas, are ongoing.
Cross border meetings have been convened between Tanzania, Uganda and Burundi.
WHO has procured and delivered four VHF kits to Kagera region to support the response.
WHO risk assessment
The risk of this MVD outbreak is assessed as high at the national level due to several concerning factors. The outbreak thus far involves 10 cases (eight probable and two confirmed), including 10 deaths, resulting in a CFR of 100%. One case was a healthcare worker, highlighting the risk of nosocomial transmission. The source of the outbreak is still unknown. The delayed detection and isolation of cases could lead to a missed chain of transmission.
The regional risk is considered high due to Kagera's strategic location as a transit hub, with significant cross-border movement of the population to Rwanda, Uganda, Burundi and the Democratic Republic of the Congo. This highlights the potential for spread into neighbouring countries. MVD is not easily transmissible (i.e. in most instances, it requires contact with the body fluids of a sick patient presenting with symptoms or with surfaces contaminated with these fluids). However, it cannot be excluded that a person exposed to the virus may travel.
The global risk is currently assessed as low. There is no confirmed international spread at this stage, although there are concerns about potential risks. Kagera region of Tanzania, while not close to the country’s capital or major international airports, is well-connected through transportation networks, and has an airport that connects to Dar es Salaam for onward travel outside Tanzania by air. This highlights the need for enhanced surveillance and case management capacities at relevant points of entry and along borders, as well as close coordination with neighbouring countries to strengthen readiness capacities.
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Source: World Health Organization, https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON554
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