More than 3,000 people have now died in the Democratic Republic of Congo’s Ebola Bundibugyo outbreak out of 6,250 confirmed cases, the Africa Centres for Disease Control and Prevention (Africa CDC) said Thursday, as the virus kills nearly half of those it infects as it outpaces efforts to contain it.

“The numbers are telling the story,” Dr Wesam Mankula, lead of the Continental Incident Management Support Team, told reporters at Africa CDC’s weekly briefing. “This outbreak is still evolving.”

At 16 weeks, the epidemic has spread over an area larger than the United Kingdom, France, and more than 35 African states. It is already the second largest Ebola outbreak in DRC’s history, and is on track to be the largest on record, with 6.5 times the caseload that the 2014 West Africa epidemic had at the same stage.

Africa CDC reports that 89% of listed contacts are being followed up, but Mankula acknowledged the number of contacts actually being identified per case falls well short of the target. Each confirmed patient should generate a list of 40 to 60 people they may have exposed, but most lists are far shorter, meaning the vast majority of potential contacts are never traced. Adjusted for that shortfall, the effective contact tracing rate drops to just 19%, Mankula said.

Without adequate tracing, many patients are never identified until it is too late. That tracing shortfall continues to play out in affected provinces, with more than 60% of deaths in the past seven days occurring in the community, with people dying before they could be reached and referred to treatment.

“This is highlighting the importance of pushing more community health workers, senior experts from the surveillance focusing on case investigation, to improve contact listing and contact tracing,” Mankula said. “Hopefully, with pushing more community health workers, we can see improvement in the community tracing.”

Weekly confirmed cases peaked at 537 during the week of 10 August and have since dipped to 464 and 479, a 12% decline Mankula called a “plateau phase,” though he cautioned a similar plateau in June was followed by a surge.

Four health zones have gone more than 42 days without new infections, the established international benchmark for interrupted transmission, and five more are in a control phase. But 51 health zones still have active transmission, and each infected person is still passing the virus to more than one other on average, meaning the outbreak continues to grow.

“It’s very still very early to say we brought this outbreak under control,” Mankula said.

The epidemic migrates into a warzone

Cases in Ituri province, the epicentre with more than 5,100 infections, fell 12% over the most recent three-week window. But as the outbreak appears to settle in Ituri, caseloads are accelerating elsewhere, Africa CDC officials said.

North Kivu, where armed groups including M23 have displaced millions in an ongoing civil war, saw cases more than double and deaths rise 98% in the same period, with the highest case fatality rate of any affected province at 67.7%.

Further north, in the remote and densely forested provinces of Haut-Uélé and Bas-Uélé bordering South Sudan and the Central African Republic, cases are surging too. Haut-Uélé cases nearly tripled in the most recent three-week window, and Bas-Uélé, the sixth province to be affected, is now reporting cases for the first time.

The conflict has made some health zones inaccessible to international and government responders, as communities and armed groups refuse entry. Mankula said responders urgently need negotiated humanitarian corridors in order “to do their function, moving from one place to another, support active case search, contact identification, contact isolation, infection prevention control measures, expanding Ebola treatment centres in those affected zones.”

Health workers in the crossfire

Violence Against Ebola Responders Mounts in DRC as Red Cross Condemns Attacks

Forty-seven healthcare workers have died from the virus out of 163 infected, according to Africa CDC briefing data presented Wednesday, up from the 43 deaths reported last week.

Beyond the virus, workers face direct violence: the Red Cross has documented 11 violent incidents in the first 100 days of the outbreak, with volunteers attacked and ambulances set on fire by communities fuelled by mistrust and misinformation. Eight health workers have been killed in attacks as of 22 August, according to the UN’s senior Ebola coordinator.

Health workers risking infection and violent assault have also faced months of delayed or missing pay, triggering repeated strikes since July. Asked about the delays, Prof Yap Boum, Africa CDC’s field manager in DRC, said the government had begun registering and paying workers in Bunya and Rampara.

“It’s been a while since you have not heard about those strikes because the government have done two things,” Boum said. “One is to ensure that they can register the staff that are working, but also starting to pay them… at least all those that were working in treatment centre.”

Boum said he expected payments to be completed by next week. Payment disputes have been a persistent obstacle to the response, and aid agencies have warned that sustained, timely compensation for frontline workers is essential to maintaining the workforce needed to contain the outbreak.

Vaccines and therapeutics in the pipeline

No licensed vaccine or treatment exists for the Bundibugyo strain of the virus, leaving health workers and communities without the protection that helped bring previous Zaire Ebola outbreaks under control. Authorities are fast-tracking several candidates through clinical trials to try to close that gap, Africa CDC said.

The Ervebo vaccine, effective against Zaire, is being deployed to frontline workers under compassionate use despite unproven efficacy against Bundibugyo. More than 1,100 healthcare workers have received it so far, and a solidarity trial is expected to begin in DRC within a week, Africa CDC reported.

“The vaccine Ervebo is effective for the Zaire strain, but its efficacy against the recent strain, the Bundibugyo, has not been demonstrated yet,” said Prof Placid Mbala, Africa CDC’s Director of Research. “But we believe that we may see some cross-protection… this is why we are using the Ervebo vaccine mostly to also evaluate the impact of this vaccine during this outbreak, and also to conduct a kind of vaccine effectiveness and efficacy study in the field.”

Phase one trials for vaccine candidates from Shaddock and Moderna are underway in the UK and Canada respectively, and Egypt’s Mina Pharma has received $16.5 million from CEPI to advance its own candidate.

Two therapeutic trials are also progressing, Mbala said. A post-exposure prophylaxis trial, which is testing whether drugs given to contacts of confirmed cases can prevent them from developing the disease, has recruited 216 of a 400-person target. If effective, they would become a vital tool in slowing transmission by protecting people before they can be infected.

A separate trial testing remdesivir and monoclonal antibodies in confirmed patients has enrolled 334 of 500. About 35 participants have so far reached the 28-day mark at which initial analysis can begin, with the first readouts expected by mid-September.

“But I think with the first 100 participants, we won’t be able to see the efficacy of these different drugs,” Mbala said. The trial’s safety monitoring board will then determine whether to continue recruitment toward the full 500 or add further therapeutics.

“It’s an adaptive protocol,” Mbala added. “We may add more therapeutics when they can be available.”

Image Credits: MSF, DRC Health Ministry.