WHO declares Ebola outbreak in eastern DR Congo and Uganda a global public health emergency

The World Health Organization on May 17 declared the Ebola outbreak centered in eastern Democratic Republic of the Congo, with confirmed cross-border spread to Uganda, a Public Health Emergency of International Concern, or PHEIC, the agency’s highest level of international alert. The outbreak involves Bundibugyo ebolavirus, a rarer Ebola virus species for which WHO says there are no approved strain-specific vaccines or treatments.

In its statement, WHO said it “is hereby determining that the Ebola disease caused by Bundibugyo virus in the Democratic Republic of the Congo and Uganda constitutes a public health emergency of international concern (PHEIC), but does not meet the criteria of pandemic emergency, as defined in the IHR.”

As of May 16, WHO reported 8 laboratory-confirmed cases in Ituri Province in northeastern Congo, along with 246 suspected cases and 80 suspected deaths. The agency said the outbreak was centered in affected health zones including Bunia, Rwampara and Mongbwalu. It also reported spread beyond the Ituri epicenter: two laboratory-confirmed cases in Kampala, Uganda, reported on May 15 and 16 among travelers from Congo, with one death, and one laboratory-confirmed case in Kinshasa, reported May 16, in a traveler returning from Ituri.

The declaration sharply raises the international profile of the outbreak because WHO says the known numbers may understate its true scale. In the same statement, the agency warned: “There are significant uncertainties to the true number of infected persons and geographic spread associated with this event at the present time.” WHO also cited community clusters, deaths and deaths among health care workers as major concerns, including signs that transmission linked to health care settings may be occurring.

The other reason this outbreak stands out is the virus itself. WHO said, “However, unlike for Ebola‑zaire strains, there are currently no approved Bundibugyo virus‑specific therapeutics or vaccines.” That sets this event apart from outbreaks caused by Zaire ebolavirus, the species behind several recent Ebola emergencies, for which licensed countermeasures exist.

A PHEIC is WHO’s top formal alarm under the International Health Regulations, the legal framework that governs how countries respond to cross-border health threats. It is reserved for extraordinary public health events that pose a risk to other countries and may require a coordinated international response.

Bundibugyo ebolavirus is less common than Zaire ebolavirus and has been linked to notable previous outbreaks in Uganda in 2007 and in Congo in 2012. For most readers, the practical significance is simple: the virus is familiar enough to be recognized as Ebola, but not the strain for which approved vaccines and therapeutics are available.

WHO said Director-General Tedros Adhanom Ghebreyesus will convene an Emergency Committee to advise on Temporary Recommendations under the International Health Regulations. Those recommendations typically guide countries on surveillance, case detection, isolation, treatment, infection prevention and cross-border measures.

For now, WHO’s operational advice is to strengthen surveillance, isolation, case management and infection control, while avoiding broad restrictions that can disrupt response efforts. The agency advises against general border closures or wide travel and trade restrictions.

Other public health groups are already moving to scale up. Africa CDC, the African Union’s public health agency, has confirmed the Bundibugyo outbreak in Ituri and called for urgent regional coordination. Médecins Sans Frontières, also known as Doctors Without Borders, said it was preparing a large-scale response. Congo had publicly declared the outbreak around May 15, and Uganda had already confirmed an imported case from Congo.

The WHO declaration means the outbreak is now being treated as an internationally coordinated health emergency. But the agency stopped short of its newer, separate threshold for a pandemic emergency, underscoring both the seriousness of the outbreak and the limits of what is known so far.