Reacción a "The WHO has declared the Ebola outbreak in the Democratic Republic of the Congo and Uganda a public health emergency of international concern"

The current outbreak in DRC and Uganda is caused by the Bundibugyo virus, a member of the species Orthoebolavirus bundibugyoense, closely related to Ebola virus (species Orthoebolavirus zairense).  

There are several reasons for concern.

First, reports that initial GeneXpert Ebola testing was negative suggest that the outbreak may have gone undetected for some time, with early diagnostic blind spots delaying recognition.

Second, infections in healthcare workers are a serious warning sign in any filovirus outbreak, because they indicate unrecognised transmission in healthcare settings and gaps in infection prevention and control.

Third, the identification of cases in Kinshasa and Kampala, hundreds of kilometres from Ituri province, shows that the virus has already moved through human mobility networks before full containment was in place.

Bundibugyo virus has caused two previously recognised outbreaks. The first was in Bundibugyo District, Uganda, in 2007–2008, with 131 reported cases and 42 deaths, and a case fatality proportion of 34–40%. The second was in Isiro, Democratic Republic of the Congo, in 2012, with 38 laboratory-confirmed cases and 13 deaths, although wider outbreak reports including probable and suspected cases gave higher totals. These figures are lower than the case fatality rates seen in many outbreaks caused by Ebola virus, but they are still extremely serious. Bundibugyo virus disease is not a mild infection.

There is a licensed vaccine that targets Ebola virus from the species Orthoebolavirus zairense (rVSV-ZEBOV). Experimental non-human primate work suggests that rVSV-ZEBOV may provide partial heterologous protection against Bundibugyo virus, but this cannot be assumed to translate into reliable protection in people during an outbreak. Adenovirus- and MVA-vectored vaccine platforms may offer broader possibilities, particularly where multivalent constructs are used, but recent immunological data suggest that some licensed or advanced platforms still induce responses that are predominantly directed against Ebola virus rather than broadly cross-reactive across all ebolaviruses. In plain terms, we do not currently have a proven, licensed, Bundibugyo-virus-specific vaccine available for outbreak control and further urgent research is required.

The same applies to therapeutics. Approved monoclonal antibody treatments such as Inmazeb and Ebanga were developed for disease caused by Ebola virus, not Bundibugyo virus, and their efficacy against other ebolaviruses has not been established. There are promising experimental broad-spectrum antibodies, but these are not yet a substitute for rapid detection, high-quality supportive care, infection prevention and control, and contact tracing.

The immediate priorities are therefore practical and scientific: Bundibugyo-virus-capable diagnostics, rapid genomic sequencing, strong infection prevention in healthcare settings, safe clinical pathways, contact tracing, community engagement, and treatment centres able to deliver high-quality supportive care. Genomic sequencing is particularly important because it can confirm the virus species, identify whether cases are linked, reconstruct transmission chains, and detect whether the outbreak reflects sustained human-to-human transmission or multiple introductions.

This outbreak also highlights a persistent weakness in epidemic preparedness. We tend to build tools around the best-known outbreak pathogens, but rarer viruses such as Bundibugyo virus can still cause severe disease and international spread. Sustained investment in high-containment laboratories, diagnostic development, genomic surveillance, vaccine platforms, therapeutics and international research partnerships is essential. These capacities cannot be assembled at speed once an outbreak is already moving.