Lancet warns lack of rapid test hampers response to Bundibugyo Ebola in DRC and Uganda

A new Lancet Comment says the Ebola outbreak caused by Bundibugyo virus in Central Africa has exposed a critical weakness in the response: there is still no reliable rapid diagnostic test for this Ebola species, even as health officials try to contain transmission in difficult conditions. In practice, that gap can slow decisions on who should be isolated, who should be retested and how quickly contacts can be traced.

The comment, published June 2, comes after the Democratic Republic of the Congo’s Health Ministry declared the outbreak in Ituri Province on May 15. Two days later, World Health Organization Director-General Tedros Adhanom Ghebreyesus determined that the epidemic in the DRC and Uganda was a Public Health Emergency of International Concern, the organization’s highest formal alarm. Africa CDC, the African Union’s public health agency, followed on May 18 with a Public Health Emergency of Continental Security. In its latest Disease Outbreak News update, dated May 29, WHO said that as of May 27 the DRC had reported 906 suspected cases and 223 suspected deaths. As of May 29, there were 134 laboratory-confirmed cases across the two countries, including nine in Uganda, and 18 confirmed deaths overall.

The central problem is that one of the most widely deployed decentralized molecular testing platforms in the region is not configured to detect this virus. In a rapid risk assessment dated May 22, WHO said GeneXpert platforms are present in many districts in the DRC and Uganda, but “this does not identify Bundibugyo ebolavirus.” That matters because GeneXpert systems are often used to bring testing closer to patients rather than relying entirely on distant reference laboratories.

For Bundibugyo Ebola, WHO says confirmation still requires nucleic acid amplification testing, or NAAT, including PCR testing. And timing matters: if the first blood sample is taken less than 72 hours after symptoms begin, testing should be repeated. Existing Ebola antigen rapid diagnostic tests can help with triage, but prior field evaluations have shown variable sensitivity, and WHO guidance does not treat them as reliable rule-out tests. In other words, a negative rapid test alone is not enough to safely exclude Ebola infection.

That diagnostic limitation has direct consequences on the ground. WHO and related assessments say the response is being complicated by insecurity, population displacement, attacks on health facilities, delays moving samples and laboratory backlogs. Uganda’s confirmed cases, reported by WHO as imported cases in Kampala and Wakiso, also show how quickly suspected infections may need to be assessed across borders. In that setting, a reliable point-of-care test would not be a technical luxury. It would help speed triage, isolation, contact tracing and the safe handling of suspected cases, while reducing the risk that infected people are missed or that uninfected people are held in Ebola treatment areas.

The virus involved here is also not the Ebola species for which the best-known licensed tools were built. Bundibugyo ebolavirus is different from Zaire ebolavirus, the species targeted by licensed Ebola vaccines and treatments. According to WHO and related assessments, there are no licensed vaccines or therapeutics specifically approved for Bundibugyo ebolavirus, and cross-protection from Zaire-targeted products in humans has not been proven.

That leaves public health authorities leaning heavily on surveillance, case finding, isolation and supportive care, while pushing to mobilize a broader emergency response. Announcing WHO’s decision, Tedros said on May 20: “Early on Sunday, I declared a public health emergency of international concern over an epidemic of Ebola disease in the Democratic Republic of the Congo and Uganda.” Africa CDC Director General Dr. Jean Kaseya said when the agency issued its continental emergency declaration: “Today, we declare this PHECS to mobilise our institutions, our collective will, and our resources to act swiftly and decisively.”