Disease Outbreak News

Sudan virus disease - Uganda

26 April 2025
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Situation at a glance

On 26 April 2025, the Ministry of Health (MoH) of Uganda declared the end of the Sudan virus disease (SVD) outbreak after two consecutive incubation periods (a total of 42 days) since the last person confirmed with SVD tested negative for the virus on 14 March 2025. A total of 14 SVD cases (including 12 confirmed cases and two probable cases) including four deaths (two confirmed and two probable) have been reported during this outbreak. WHO and partners provided technical, operational and financial support to the government to contain the outbreak. Although the outbreak has been declared over, health authorities are maintaining surveillance to rapidly identify and respond to any re-emergence. Risk communication and community engagement will also continue to ensure the community stay informed and stigma to those who were affected is minimized.

Description of the situation

Since the third disease outbreak news on this event published on 8 March 2025, no new confirmed cases of Sudan virus disease (SVD) have been reported. The outbreak was declared in Uganda on 30 January 2025, and as of 25 April 2025, 12 confirmed and two probable cases have been reported, including four deaths (two confirmed, two probable) with a case fatality ratio (CFR) of 29%. The age range of confirmed cases is 1.5 years to 55 years, with a mean age of 27 years. Males accounted for 55% of the total cases. The cases were reported from seven districts in the country which comprise Fort Portal City, Jinja, Kampala, Kyegegwa, Mbale, Ntoroko, and Wakiso (Figure 1).

Ten of the confirmed cases received care at SVD treatment centres, including the last two cases who were discharged on 15 March 2025. As of 24 April 2025, 534 contacts were identified and followed up in Fort Portal City, Jinja, Kampala, Mbale, Ntoroko, and Wakiso.  

On 26 April 2025, the Ministry of Health of Uganda declared the end of the outbreak. This declaration came after two consecutive incubation periods (a total of 42 days) since the last person confirmed with SVD tested negative for the virus for the second time on 14 March 2025, according to WHO recommendations.

Figure 1: Distribution of Sudan virus disease (SVD) confirmed, and probable cases reported from Uganda between 30 January and 25 April 2025

DON map SVD Uganda

Figure 2:  Epidemiological curve of reported confirmed and probable SVD cases by symptom onset date, data as of 25 April 2025, (n=14) 

SVD Uganda Epi curve

Epidemiology

Sudan virus disease is a severe disease, caused by a virus, Sudan virus (SUDV), belonging to the same family as Ebola virus. It can result in high case fatality. It is typically characterized by acute onset of fever with non-specific symptoms/signs (e.g., abdominal pain, anorexia, fatigue, malaise, myalgia, sore throat) usually followed several days later by nausea, vomiting, diarrhoea, and occasionally a variable rash. Hiccups may occur. Severe illness may include haemorrhagic manifestations (e.g., bleeding from puncture sites, ecchymoses, petechiae, visceral effusions), encephalopathy, shock/hypotension, multi-organ failure, and spontaneous abortion in infected pregnant women. Individuals who recover may experience prolonged sequelae (e.g., arthralgia, neurocognitive dysfunction, uveitis sometimes followed by cataract formation), and clinical and subclinical persistent infection may occur in immune-privileged compartments (e.g., central nervous system, eyes, testes). Person-to-person transmission occurs by direct contact with blood, other bodily fluids, organs, or contaminated surfaces and materials with transmission risk beginning at the onset of clinical signs and increasing with disease severity. Family members, health and care providers, and participants in burial ceremonies with direct contact with the deceased are at particular risk. The incubation period ranges from 2 to 21 days, but typically is 7–11 days. 

Public health response

Health authorities implemented public health measures, including but not limited to the following:

Coordination:

  • The Ministry of Health activated the coordination structures at national and subnational levels, including the National Task Force and the Incident Management Team, and dispatched Rapid Response Teams to the affected districts.
  • The country developed a National Response Plan (February-April 2025). The response plan was updated to reflect the response priorities and builds on lessons learned from previous outbreaks. It deployed packages of activities across the districts according to risk.

Surveillance and contract tracing:

  • MoH with support from WHO and partners, conducted alert management including the setup of an alert desk with toll-free numbers to detect and verify alerts from all over the country that meet the case definition. Since 30 January, 3757 signals were reported from all over the country and 2700 alerts verified as suspected cases.
  • MoH with support from partners allocated teams to conduct detailed case investigations around all confirmed and probable cases to identify and stop the chains of transmission.
  • MoH allocated teams to conduct contact listing of cases and perform daily follow-up of contacts.
  • Following the declaration of the outbreak, MoH, with support from WHO, established mortality surveillance. Over 2940 non-trauma deaths were tested in communities and health facilities located in the affected districts, and one case tested positive.
  • MoH conducted exit screening of SVD signs and symptoms among travelers at Uganda’s 13 priority points of entry including Entebbe International Airport

Case Management:

  • MoH with support from WHO and partners set up four designated isolation and treatment units in Fort Portal, Jinja, Kampala, and Mbale where confirmed cases receive optimized supportive care.
  • MoH scaled up its case management strategy to ensure sufficient capacities to provide care for all probable and confirmed cases in all hotspots.
  • Patients who recovered from the disease were included in the survivor care programme for support and care.

Laboratory:

  • MoH and partners strengthened laboratory capacities and deployed a mobile laboratory to Mbale to reduce turnaround time for laboratory results.
  • MoH performed full genome sequencing on the sample of the first confirmed case and findings indicate the outbreak was most likely the result of a spillover event from a zoonotic reservoir. Sequencing was also performed on samples of subsequent confirmed cases.

Infection prevention and control (IPC):

  • MoH activated the IPC response coordination mechanism including the IPC ring around cases, which included cleaning and disinfection of sites where confirmed cases passed through.
  • MoH provided recommendations to health workers, district leaders, and the public to strengthen detection of suspected cases and implement appropriate infection, prevention and control measures.
  • MoH strengthened IPC activities, with the support of partners, notably to improve screening, isolation and notification at health facilities in order to better detect suspected cases.

Risk communication and community engagement (RCCE)

  • An integrated community engagement approach was adopted where the RCCE team supported other response teams to gain access to communities. This approach built trust and improved efforts in contact tracing, case investigation, community surveillance, referrals to isolation units and the delivery of psychosocial support.
  • Anthropological investigations in communities with confirmed cases were essential for an effective response to identify community concerns, risk behaviours, reduce hesitancy from communities and to enhance evidence-informed decisions across pillars.
  • Risk communication messages were strategically developed and widely disseminated to encourage protective and health-seeking behaviors. At the same time, ongoing community engagement efforts with religious leaders, schoolteachers, traditional healers and other local influencers helped build trust and supported community cooperation with broader response efforts.   

Research and development

  • Research priorities: The Collaborative Open Research Consortium (CORC) for the Filoviridae Family held two global consultations to deliberate and identify the research priorities for Sudan ebolavirus in general and this outbreak in particular. Over 200 scientists from around the world participated in each of the two consultations.
  • Ring vaccination trial: Uganda’s Ministry of health, with support from WHO and its partners, launched a vaccine trial against the Ebola Sudan virus, the first to assess the clinical efficacy of a vaccine specific to the Ebola Sudan virus.  The trial was initiated only four days following the outbreak declaration, reflecting the urgency of the response while maintaining rigorous ethical and regulatory standards. After the outbreak was confirmed on 30 January, researchers from the Uganda Makerere University and the Uganda Virus Research Institute (UVRI), with support from WHO, conducted the vaccination trial and rings of contacts of all confirmed cases were defined and randomized. The trial followed the ring vaccination protocol, in which contacts of confirmed cases are offered the vaccine in rings that are randomized to receive the vaccine immediately or later to assess vaccine efficacy, safety and immunogenicity.
    • The protocols and research priorities were developed in an open collaborative approach via the Marburg virus vaccine (MARVAC) Consortium and via the Collaborative Open Research Consortium (CORC) for the Filoviridae Family. This was possible because of the dedication of Uganda’s health workers, the involvement of communities, the Ministry of Health of Uganda, Makerere Lung Institute and UVRI, and research efforts led by WHO involving hundreds of scientists through its research and development Filoviruses network. Vaccines were donated by International AIDS Vaccine Initiative (IAVI), funding support was provided by the Coalition for Epidemic Preparedness Innovations (CEPI), European Union Health Emergency Preparedness and Response (EU HERA) and Canada’s International Development Research Centre (IDRC), with further support from Africa CDC.
      • Therapeutics trial: Several candidate therapeutics are currently advancing through clinical development, no licensed treatment is yet available to effectively address potential future outbreaks of Ebola disease caused by the Sudan virus species. The therapeutics trial did not receive the required Ethics and Regulatory approvals in Uganda and it was not initiated.
      • IAVI donated their candidate vaccine, MappBio provided their candidate Sudan monoclonal, and Gilead provided remdesivir, an antiviral.

WHO supported the national authorities through:

  • Risk assessment, active case search, alert notification, case investigation, contact tracing and epidemiological analyses.
  • Providing operational, financial and technical support to the Ministry of Health to ensure swift response. A total of US$ 3.4 million was released from the Contingency Fund for Emergencies for the three levels of WHO to support the government-led response. Additionally, a total of US$ 4.1 million was mobilized from donors to support the response.
  • Supporting the national laboratory system to implement sample collection, transport and diagnostic testing and providing RT-PCR testing kits.
  • Providing strategic, technical and operational support to strengthen infection prevention and control response measures and standards within health facilities and Ebola treatment units in Kampala, Mbale, Luwero districts. This includes supporting IPC ring activation activities, rapid assessments of health facilities, capacity building of health workers, mentorship and supportive supervision at designed health facilities and supporting development of key guidance, SOPs and tools.   
  • Facilitating access to candidate vaccines and therapeutics and supporting the launch of the vaccine trial. Rings were defined around all confirmed cases and their contacts were invited to consent in the trial.  As part of this support, the "TOKEMEZA SVD" vaccine trial was launched on 3 February 2025 and the TOKOMEZA immuno (an add-on study) was launched on 1 March 2025.
  • Providing technical and operation assistance for the setup of isolation centres for suspected cases and two SVD treatment units in Kampala and Mbale.
  • Mobilizing logistics to complement government supplies, including IPC supplies, drugs, resuscitation and monitoring equipment, admission packages, and mattresses.
  • Deploying a team of 67 experts to Jinja, Kampala, Mbale, and Wakiso districts to support across different response pillars including coordination, surveillance, laboratory, logistics, IPC, RCCE, and case management pillars.
  • Supporting RCCE efforts to counter misinformation and enhance community engagement through the deployment of two anthropologists.
  • Intensified and integrated risk communication and community engagement, including sensitization and training of Village Health Teams, traditional healers, religious leaders and teachers. 
  • Collecting social and behavioural data and using evidence to respond to communities’ anxieties and concern, rumours, misinformation and disinformation

WHO risk assessment

The outbreak is declared over, as of 26 April 2025 with no new cases reported for 42 consecutive days.

Sudan virus disease (SVD) is a severe, often fatal illness affecting humans. Sudan virus (SUDV) was first identified in southern Sudan in June 1976. Since then, the virus has emerged periodically and prior to this outbreak, eight outbreaks caused by SUDV have been reported, five in Uganda and three in Sudan. The case fatality rates of SVD have varied from 41% to 70% in past outbreaks.

SUDV is enzootic and present in animal reservoirs in the region. Uganda reported five previous SVD outbreaks (one in 2000, one in 2011, two in 2012, and one in 2022). The most recent SVD outbreak was declared over on 11 January 2023. A total of 164 cases with 55 deaths were reported in nine districts. The current outbreak is the sixth SVD outbreak in Uganda.

This outbreak showed that re-emergence of SVD is a major public health concern in Uganda.  Strengthening of surveillance capacities can help to detect future outbreaks, preventing further spread.

An investigation is ongoing to determine the source and the scope of the outbreak to ensure no hidden chains of transmission exist and to inform future risk reduction efforts.

WHO advice

Effective Ebola disease outbreak control, including SVD, relies on applying a package of interventions, including case management, surveillance and contact tracing, a strong laboratory system, implementation of infection prevention and control measures in health care and community settings, safe and dignified burials and community engagement and social mobilization.

Risk communication and community engagement is crucial to successfully controlling SVD outbreaks. This includes raising awareness of symptoms, risk factors for infection, protective measures and the importance of seeking immediate care at a health facility. Sensitive and supportive information about safe and dignified burials is also crucial. Awareness should be built through targeted campaigns and direct work with affected and proximate communities, with special attention to engage with traditional healers, clergy, ‘boda boda’ drivers and community leaders, who are important sources of information for the community. Findings from rapid qualitative assessments should be implemented to collect socio-behavioural data, which can then be used to inform response pillars. Priority areas to strengthen, based on recent evidence are mortality surveillance, contact tracing and safe and dignified burials.  Misinformation and rumours should be addressed to foster trust and promote early symptom reporting.

Early initiation of intensive supportive treatment increases the chances of survival. All above-mentioned interventions need to be thoroughly implemented in affected areas to stop chains of transmission and decrease disease mortality. Cases, contacts and individuals in affected areas who present signs and symptoms compatible with case definitions should be advised not to travel and to seek early care at designated facilities to improve their chances of survival and limit transmission.

WHO encourages countries to implement a comprehensive care programme to support people who have recovered from Ebola disease with any subsequent sequelae and to enable them to access body fluid testing and to mitigate the risk of transmission through infected body fluids by adequate practices.

Collaboration with neighbouring countries should be enhanced to harmonize reporting mechanisms, conduct joint investigations, and share critical data in real-time. Surrounding countries should enhance readiness activities to enable early case detection, isolation and treatment.

A range of candidate vaccines and therapeutics are under different stages of development. Since 2020, WHO has convened scientific deliberations and set up an independent process to review candidate medical countermeasures (MCMs) prioritization and clinical trial designs. One candidate vaccine and two candidate therapeutics (a monoclonal antibody and an antiviral) have been recommended and are available in country and are being assessed (clinical efficacy and safety) through randomized clinical trial protocols.

Thanks to preparedness measures that the government took after the previous outbreak in 2022, and a global research collaboration led by WHO (first MARVAC now FILOVIRUS CORC), a trial of a candidate vaccine was launched just four days after the outbreak was declared.

Based on the current risk assessment and prior evidence on Ebola disease outbreaks, WHO advises against any travel or trade restriction to Uganda.

Further information

Citable reference: World Health Organization (26 April 2025). Disease Outbreak News; Sudan virus disease in Uganda. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON566