Tanzania confirms its second MVD outbreak: A constantly emerging outbreak calls for effective countermeasures in light of one health approach and preparedness to counter future epidemics

The Republic of Tanzania recently confirmed one case of Marburg virus disease (MVD) in the Kagera region [1,2]. After laboratory confirmation of suspected sample, the Tanzanian President announced it on 21 January 2025 referring to its occurrence in the North-Western Kagera region [1]. The same was briefed to the press alongside the Director General of the World Health Organisation (WHO). The laboratory test initially conducted at the Kabaile mobile laboratory in Kagera was later confirmed by the better-equipped centralised laboratory at Dar-es-Salaam, the capital city [1]. As of 20 January 2025, all the 25 MVD suspected Tanzanian cases were reportedly negative and were being closely monitored [1]. The event information site (EIS) of the WHO had informed about these cases in the Kagera region earlier, on 13 January 2025 [3]. The EIS issues rapid alerts from time to time about the acute and rapidly developing public health risks and events with possible international implications to its member states.

The MVD outbreak risk in Tanzania is assessed as high due to several compelling factors. MVD reports in Bukoba district in the first outbreak in 2023 and three districts of Kagera region and two districts (Biharamulo and Muleba) in the second outbreak recently in 2025 suggested the occurrence of the geographical spread of the virus [2,3]. Delayed diagnosis and late case isolation in the recent outbreak were attributed to the lack of reliable data to facilitate rigorous case identification. In light of this, national team was recently deployed to investigate and respond quickly. Healthcare workers are more susceptible to MVD within the vulnerable population as it is nosocomially transmitted [3]. Although the source of the current outbreak was unknown, fruitbat is reportedly endemic there as the zoonotic reservoir [3]. Although mobile testing laboratory was located in Kagera, suspected samples were sent to the better-equipped national public health laboratory at Dar-es-Salaam for confirmation [1]. Treatment units need to be established in the region alongside the intensified surveillance.

As per the latest report, Tanzania declared end of MVD crisis after two confirmed and eight probable cases, on 13 March 2025 [4]. This declaration came after 42 days (which means two consecutive incubation periods) after the last reported confirmed case. No new confirmed or probable case was reported after the last confirmed death on 28 January 2025. Also, the eight probable cases died before the outbreak was confirmed. All the 10 (two confirmed and eight probable) cases with 100 % CFR (case fatality ratio) during this outbreak were reported from Biharamulo district of Kagera region [4]. A possible index case was an adult female who died on 16 December 2024. A total of 281 contacts (with 21-day complete follow-up) were listed till 12 March 2025. Table 1 describes the current MVD outbreak in detail [4]. The Tanzanian authority has demonstrated its capabilities to contain a similar outbreak in the past too. The recent 2025 Tanzanian outbreak is the second one, the first being recorded in March 2023 in Bukoba district, Kagera. The first Tanzanian outbreak in 2023 that lasted for nearly two months had reported nine (eight confirmed, one suspected) cases with six deaths (67 % CFR) [3].

Table 1.

Description of the 2025 MVD outbreak in that occurred in Tanzania.

Case description	No. of cases	Clinical details	CFR	Median age (Yrs)	Gender differentiation
Confirmed cases	02	Laboratory testing	100 %	30 (1–75)	70 % females
Probable cases	08	Died before the outbreak was confirmed
Suspected cases	108	106 tested MVD-negative	–	–	–
Contacts	272	21-day follow-up completed	–	–	–

Source: https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON559 (accessed April 15, 2025) [4].

‘Marburg’ name was coined after its first report in Marburg city, Germany in 1967. Marburg virus (MARV; Marburgvirus genus) is enveloped, single-stranded, negative-sense RNA (filo) virus of Filoviridae family [5,6]. The family has a single (Marburg marburgvirus) species of two strains, Marburg virus (MARV) and Ravn virus (RAVV) [5]. Both are filoviruses, same as Ebola virus. Capable of causing high-CFR outbreak, the clinical manifestation of MVD is similar to Ebola [7]. This rare viral hemorrhagic fever sporadically occurred in many African countries infrequently with 22.6–100 % CFR. The recorded MVD outbreaks in Africa were in Angola, DRC, Ghana, Kenya, Equatorial Guinea, Rwanda, South Africa and Uganda. With 2–21-day incubation, its commonly encountered symptoms include fever, chills, headache, sore throat, muscle-ache, chest pain, rash, nausea, vomiting, diarrhoea, followed by an unexplained bleeding later [6,7]. It causes severe haemorrhagic symptoms in seven days (highly virulent). In light of this, the CDC categorised MVD as level 1 (recommended to practise usual precautions) [8].

It spreads by direct contact with the blood or body fluids of a patient and also through contaminated objects (fomites) like clothing, bedding, etc. within the household and clothing, bedding, needles and other medical equipments in a medical setting. It also spreads by zoonotic transmission through direct contact with infected fruitbat (natural reservoir) and non-human primates like chimpanzee, gorilla, monkey, etc. [6,7]. MVD is often fatal and early and timely symptomatic treatment, supportive care and hydration may improve survival rates as no licensed treatment or vaccine is currently available to effectively manage it [1]. Several promising vaccine and drug candidates are currently under clinical trials, and till then prevention seems a better option against this deadly virus to reduce human exposure risk.

Out of the many promising MVD vaccines, the TAG-CVP (technical advisory group for candidate vaccine prioritisation) of the WHO recommended clinical trials of four viral-vectored vaccine candidates to evaluate their safety, efficacy and immunogenicity [9]. Two out of the four viral-vectored vaccines are the recombinant VSV (Vesicular Stomatitis Virus) vaccine developed by the IAVI (International AIDS Vaccine Initiative) in association with the Public Health Vaccines LLC, while the other two were developed by the Sabin Vaccine Institute (that used chimpanzee adenovirus platform ChAd3) and the University of Oxford (that used chimpanzee adenovirus platform ChAdOx1) [9]. While the Phase I clinical trial data for the remaining vaccine candidates were awaited, the same for Sabin ChAd3-vectored vaccine is available. 40 clinically healthy adult humans were intramuscularly administered a single dose of cAd3-Marburg vaccine in Phase I (first-in-human) study. Results revealed that 38 out of the 40 volunteers (95 %) developed glycoprotein-specific antibody response four weeks after being vaccinated with no serious adverse events [10]. Of all those who exhibited such response, 70 % maintained it till 48 weeks. With the promising outcome of Phase I, Sabin Vaccine Institute launched the ongoing Phase II trial in Uganda and Kenya involving both not-so-old (18–50 years) and the elderly (51–70 years) age-groups [11]. Vaccination campaign targeting the healthcare workers and the vulnerable population was launched with Sabin cAd3-Marburg vaccine trials in response to the recent Rwanda MVD outbreak, to safeguard from contracting MARV [12]. The Rwandan Ministry of Health announced the introduction of Remdesivir and monoclonal antibodies as therapeutics for MVD patients [13]. Preventive cautionary measures remaining critical and important presently, effective and sustainable MVD vaccine is hoped to be developed soon as a respite against the menace of the deadly MARV in the region.

The centres for disease prevention and control (CDC), Africa deployed a mission-mode 12-member public health expert team in Tanzania to provide a robust support to contain the emergent threat [2]. Involving risk communication, prevention and control of the infection, and extending laboratory expertise, this multi-skilled epidemiologist team provided diagnostics, infection prevention and control and surveillance support on ‘ground zero’, as also engaged the community. The CDC has recently committed US$ 2 million to immediately support and revamp the governmental efforts in Tanzania [2]. The African CDC has also dispatched PCR test and genomic sequencing kits. The WHO supports the Tanzanian health authorities for enhanced outbreak response. Enhancing the diagnostic (for suspected samples) and sequencing capabilities (for positive samples) of public health laboratories in Tanzania was essential. MVD being potentially pandemic, it is an open call for international agencies, NGOs and global stakeholders to strengthen local healthcare system with improved disease surveillance, emergency response and disease control to prevent future outbreaks.

Suspected or confirmed MVD patients should immediately seek care in healthcare facilities for early medical interventions. Healthy individuals at family and community levels should avoid close contacts with symptomatic individuals, their body fluids or the items and surfaces used by them to prevent human-human viral transmission [3,6,7]. It is suggested that the male MVD survivors should have safe-sex at least for 12 months to minimise the transmission risk [6]. Close monitoring of healthcare workers and persons who might have deliberately or accidentally contacted the suspected or confirmed subjects need to be ensured. Healthcare workers treating or caring the suspected or confirmed MVD patients within medical settings must always wear appropriate PPE (personal protective equipment) kits and practise frequent hand-sanitisation to avoid infection [6]. Critical infection prevention and control (IPC) measures are recommended to implement and/or strengthen in all the healthcare facilities that are meant to treat the suspected or confirmed cases so as to minimise the transmission risks.

Multi-level and multi-sector coordination and seamless sharing of detailed situational reports shall produce encouraging outcome. Robust community-level surveillance in vulnerable areas would promptly recognise fresh cases, track family members and trace contacts. Also, diagnostic challenge is another factor for possible unreported or unaccounted data as the initial clinical presentations are similar to few other infectious diseases. The recent outbreak might have unrecognised or unreported cases too. The biowastes generated within healthcare facilities may be safely collected, transported and disposed following the laid-down guidelines [3]. Raising public awareness and engaging the community could help control any outbreak, including MVD. In similar lines, educating the community at greater risk and the public in general about the risks, transmission route and the various precautionary measures is suggested. Psychological support to the affected subject and family members to mitigate the long-term impact of the outbreak is also suggested.

Suspected cases were reported in contiguous districts bordering the international boundary, highlighting the possibilities of viral spread to neighbouring nations. Kagera region shares its border with Rwanda, Uganda and Burundi respectively on the West, North and South thereby making these countries vulnerable with high regional risk (Fig. 1). Kagera is a transit hub and significantly high cross-border movements occur across Rwanda, Uganda, Burundi and the Democratic Republic of the Congo (DRC). Kagera is well-connected by road and air networks; the airport connects to the capital Dar-es-Salaam for inward and outside travelling. As MVD transmits through direct contact with body fluids of the infected or the surfaces contaminated by them, its transmission during travelling could not be ruled out.

Fig. 1.

The transit hub Kagera of Tanzania (in green) with the 2025 MVD outbreak. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Source: https://wwwnc.cdc.gov/travel/notices/level1/marburg-tanzania (accessed January 21, 2025) [8]

Although global risk for MVD is assessed as low in current scenario, enhanced surveillance and revamped case management facilities are needed, especially at entry-exit points. Close coordination with the neighbouring countries is essential to strengthen the preparedness [3,4]. Collaborations on account of reporting mechanisms, joint investigations and sharing critical data on real-time bases with the neighbouring countries need to be enhanced. Local health authorities were engaged in identifying infected persons and transmission source to prevent further transmission.

As fruit-bat is the only known natural reservoir, avoiding contact with it and other suspected carriers/reservoirs like the non-human primates in the region is suggested. As bushmeat (of monkeys, forest antelopes, bats, etc.) reportedly transmit MARV, thorough and deep cooking of animal products before consumption is suggestible [14]. Fruitbat is endemic to the region, and hence people who either work or visit mines or caves inhabited by these may use appropriate protective gears (like PPE) to reduce the spillover (bat-human) transmission risk [6,7,14]. Human habitat nearby could avoid consuming the fruits partially eaten by bats. Government organisations, health agencies, NGOs and researchers could conduct serological surveys collaboratively on the communities and assess livelihood options in high-risk region. They could collect critical data on the work-places and the associated risks not only from fruitbat (Egyptian rousette bat) but also other wild and domesticated ones like chimpanzee, gorilla, monkey, baboon, marmoset, forest antelope, mice, hamster, guinea pig, etc. in line with the ‘One Health’ model. As pig is reportedly susceptible to filovirus infection, it could be a potential amplifier [6,14]. Precautionary measures are therefore highly needed in piggery to prevent viral transmission. Avoiding direct contact with dead bodies and contaminated fomites in the burial rituals is also suggested.

Diverse surveillance measures to analyse MVD dynamics may be implemented. Easy-to-understand brochure (possibly in vernacular languages) describing spillover and spillback risks of the virus may be developed to help mitigate community-level risks [15]. Conducting comprehensive studies to analyse the effect of seasonal variations on high transmission risks to educate vulnerable communities and empower them is also suggested. High-risk Kagera region and the contiguous nations may enhance their readiness measures with a clear focus on detecting the case early, isolating/quarantine the affected/suspected population and treating the confirmed cases. To ensure a foolproof long-term solution, all human-human or animal-human transmission routes need to be identified, thoroughly studied and effectively plugged.

CRediT authorship contribution statement

Ranjan K. Mohapatra: Writing – original draft, Supervision, Conceptualization. Alok Ranjan Sahu: Writing – original draft, Validation, Data curation. Snehasish Mishra: Writing – review & editing, Project administration. Saroj Kumar Tiady: Writing – original draft, Validation. Lawrence Sena Tuglo: Writing – original draft, Validation, Methodology.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability

No data was used for the research described in the article.