The current Ebola outbreak is a public health emergency of international concern (original) (raw)

The Ebola outbreak reported to the World Health Organization (WHO) on 5th May is now believed to have resulted in 139 deaths in the Democratic Republic of Congo. The current outbreak is of particular concern due to the high fatality rate of the causal Bundibugyo strain, its spread into neighboring Uganda, and the absence of an approved vaccine or targeted treatments. Following the WHO’s declaration on 17th May that the outbreak constitutes a public health emergency of international concern[1](/articles/s41467-026-73746-1#ref-CR1 "WHO: Epidemic of Ebola Disease caused by Bundibugyo virus in the Democratic Republic of the Congo and Uganda determined a public health emergency of international concern. https://www.who.int/news/item/17-05-2026-epidemic-of-ebola-disease-in-the-democratic-republic-of-the-congo-and-uganda-determined-a-public-health-emergency-of-international-concern

             (2026)."), we outline the urgent need for sustained research into diagnostic tools, life-saving vaccines, and antiviral therapies directed against this virus.

The Bundibugyo virus (BDBV) is distinct from the Zaire Ebola virus strain, which has been responsible for the majority of documented outbreaks, including the 2014–2016 West African epidemic that resulted in more than 28,000 cases and a fatality rate of 63%[2](/articles/s41467-026-73746-1#ref-CR2 "WHO: Ebola outbreak 2014-2016 - West Africa. https://www.who.int/emergencies/situations/ebola-outbreak-2014-2016-West-Africa

             (2016)."). In contrast, BDBV has demonstrated lower viral replication compared to the Zaire strain[3](/articles/s41467-026-73746-1#ref-CR3 "Gupta, M. et al. Reduced virus replication, proinflammatory cytokine production, and delayed macrophage cell death in human PBMCs infected with the newly discovered Bundibugyo ebolavirus relative to Zaire ebolavirus. Virology 402, 203–208 (2010)."), a comparatively lower fatality rate of 30–50%, and has previously been associated with only two Ebola outbreaks in 2007 and 2012[4](/articles/s41467-026-73746-1#ref-CR4 "Levine, C. B. et al. Comparison of Zaire and Bundibugyo Ebolavirus polymerase complexes and susceptibility to antivirals through a newly developed Bundibugyo minigenome system. J. Virol. 95. 
              https://doi.org/10.1128/jvi.00643-21
              
             (2021).").

What, therefore, accounts for the designation of the current BDBV outbreak as a public health emergency of international concern?

From a disease-control perspective, two factors are important to consider. First, standard diagnostic assays for Ebola viruses frequently fail to detect BDBV, unlike the Zaire strain, raising the likelihood that case numbers are underestimated and that the true extent of transmission remains uncertain. Second, the absence of approved vaccines or targeted therapies for BDBV heightens the risk of progression to the late stages of disease, which are characterised by gastrointestinal manifestations, organ dysfunction, and, in some cases, internal haemorrhaging. These clinical challenges are further compounded by structural and political constraints that impede comprehensive public health responses in the affected regions, such as ongoing humanitarian crises, and high population mobility.

Animal studies of vaccine candidates5,6,7 for prophylaxis and monoclonal antibodies8 for treatment have so far demonstrated efficacy. A key priority for strategies will be establishing whether these interventions provide cross-protection against other Ebola viruses and related viruses to help mitigate the risk of future outbreaks.

As this situation continues to evolve and remains a serious public health concern, the rapid and transparent sharing of scientific evidence is essential. To support this effort, Nature Communications will actively consider manuscripts that provide timely and rigorous insights into the current outbreak. This includes work on genomic surveillance, public health responses, pathology, epidemiology and clinical case reporting. In particular, we welcome studies that advance diagnostic capabilities and the development of vaccines and therapeutic strategies. We encourage submissions that contribute meaningfully to these aims and help build the scientific foundation needed for an effective international response.

References

  1. WHO: Epidemic of Ebola Disease caused by Bundibugyo virus in the Democratic Republic of the Congo and Uganda determined a public health emergency of international concern. https://www.who.int/news/item/17-05-2026-epidemic-of-ebola-disease-in-the-democratic-republic-of-the-congo-and-uganda-determined-a-public-health-emergency-of-international-concern (2026).
  2. WHO: Ebola outbreak 2014-2016 - West Africa. https://www.who.int/emergencies/situations/ebola-outbreak-2014-2016-West-Africa (2016).
  3. Gupta, M. et al. Reduced virus replication, proinflammatory cytokine production, and delayed macrophage cell death in human PBMCs infected with the newly discovered Bundibugyo ebolavirus relative to Zaire ebolavirus. Virology 402, 203–208 (2010).
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The current Ebola outbreak is a public health emergency of international concern.Nat Commun 17, 4603 (2026). https://doi.org/10.1038/s41467-026-73746-1

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