DRC Ebola outbreak reaches 7,773 confirmed cases

The Democratic Republic of the Congo (DRC) recorded 7,773 confirmed cases of Bundibugyo-virus Ebola and 3,759 deaths through September 21, according to an ECDC update posted September 23. A WHO surveillance table displays the same government-reported figures. The update concerns an outbreak first detected in May, rather than a new outbreak.

Scale and surveillance

The DRC reported the figures on September 22. They were 40 confirmed cases and 27 reported deaths above the preceding report. Those changes do not establish that all the additional infections and deaths occurred in one day: cumulative figures can be revised as surveillance data are reconciled.

The cumulative death count is approximately 48% of confirmed cases. That proportion does not measure the fatality risk for every person infected, because the outbreak’s full extent, including undetected infections, remains unknown. ECDC says the DRC figures remain under review.

ECDC reported cases in 63 health zones across seven provinces. Ituri had 5,966 confirmed cases and 2,737 deaths; North Kivu had 1,438 cases and 872 deaths. WHO describes this as the largest Ebola outbreak recorded in the DRC, regardless of virus species.

ECDC reported 839 patients hospitalised in isolation and 84.5% of identified contacts under follow-up. The geographic spread and the number of people requiring care or monitoring place substantial demands on case detection and contact tracing. WHO says insecurity and displacement impede those activities.

Vaccine evidence and outbreak control

Ervebo is licensed for Ebola disease caused by Ebola virus, formerly called Zaire ebolavirus. It is not licensed specifically for Bundibugyo virus. WHO guidance published September 1 says its clinical protection against Bundibugyo-virus disease in humans is unknown and recommends its use in this outbreak only within research protocols.

In August, an international vaccine-stockpile group allocated 70,000 Ervebo doses to the DRC. The allocation designated 20,000 doses for a Phase 3 trial and 50,000 for frontline and health workers. Whether vaccination prevents disease caused by this virus, and what effect it will have on the outbreak, remains to be established.

Containment therefore depends on identifying cases, isolating and caring for patients, tracing contacts, and preventing exposure during care and burials. WHO says improved surveillance and the reconciliation of previously unreported data can raise cumulative totals alongside ongoing transmission. The eventual size of the outbreak remains uncertain.

Regional risk

Uganda reported 20 confirmed cases and two deaths in this outbreak and subsequently declared its outbreak ended. Transmission continued in the DRC. On September 21, ECDC said it was deploying two epidemiologists to reinforce the response under the leadership of the DRC health ministry and WHO.

WHO assessed the risk as very high in the DRC, high in countries sharing its land borders and low globally. ECDC assessed the risk of importation into the EU/EEA as very low. Continued transmission in the DRC warrants cross-border surveillance without implying the same level of risk in every region.