A surge in violence and unrest has forced Ebola responders in the city of Beni in the eastern Democratic Republic of the Congo to remain indoors for the past week — hampering efforts to contain the virus.

The World Health Organization (WHO) has temporarily evacuated one-third of its 120 staff members stationed in the city. Those who remain have largely stopped tracing the contacts of people diagnosed with Ebola, who they would normally vaccinate and monitor for signs of infection.

As a result, “we expect Ebola cases to rise”, says Christian Lindmeier, a spokesperson for the WHO in Geneva, Switzerland. That “will only add to the suffering of already overburdened communities” by prolonging the outbreak, WHO director-general Tedros Adhanom Ghebreyesus wrote on Twitter on 26 November.

Ebola has infected more than 3,300 people in the eastern Democratic Republic of the Congo (DRC) since August 2018 and killed nearly 2,200, according to the DRC government.

Over the past three weeks, an armed group called the ADF (Allied Democratic Forces) has terrorized residents of Beni and nearby areas with machetes and knives. At least 77 people have been killed and many more displaced, according to the Congo Research Group at New York University. The ADF is one of dozens of armed groups that operate in the DRC.

The latest surge in violence has angered residents of Beni and nearby communities, who are upset that United Nations peacekeeping troops and DRC soldiers stationed in the city have not stopped the ADF attacks. On 25 November, street demonstrations against the UN spilled into one of the organization’s compounds near Beni, where protesters set a vehicle on fire. Soon afterwards, UN troops were evacuated from the city by helicopter.

The pause in the fight against Ebola is particularly discouraging to Marie-Roseline Darnycka Bélizaire, an epidemiologist coordinating the WHO’s response to the DRC outbreak. She had begun to let herself envision the end of the outbreak, because the number of new infections reported each week has dwindled steadily since October.

Ebola responders are now able to bring many sick people to treatment centres within 24 hours of the first symptoms of infection. There, those who are ill receive drugs that can cure up to 90% of Ebola cases if given soon after infection — and they are prevented from transmitting the virus to others.

Now Bélizaire fears that more than a year of hard work by Ebola responders could be undone. Two people have been diagnosed with the virus in Beni and nearby Oicha amid the unrest — and Ebola responders haven’t been able to track chains of transmission.

“We were so close,” says Bélizaire, who is readying a WHO facility in Mangina, DRC, for an influx of Ebola responders from Beni, which is 40 minutes away.

Some of her colleagues are fearful that they, too, could be injured or killed by the ADF. But Bélizaire says they will keep pushing to end the outbreak nonetheless.

“Most of us are energized,” she says. “We want to stay in the field and finish the job.”