The head of the World Health Organization has called for an immediate ceasefire in the Democratic Republic of Congo to help tackle the Ebola outbreak.

In an open letter, Tedros Adhanom Ghebreyesus pledged to spare no effort to contain the outbreak. Suspected cases in eastern Congo are nearing 1,000, with at least 220 suspected deaths. The security situation remains very difficult, with conflict and displacement hampering response efforts.

“We cannot do this work if those who are trying to help are prevented from doing so or put in danger,” Ghebreyesus wrote. He made a direct appeal to all warring parties in the Ituri region: “Please, declare a ceasefire. Even briefly. Even just enough to let health workers through.”

Ghebreyesus noted that this outbreak is caused by the Ebola Bundibugyo virus, for which there are no approved vaccines or treatments, unlike previous outbreaks. “While there are no specific treatments for Bundibugyo, there is much we can do together to prevent the spread of this virus and save lives,” he added.

More than 90% of cases have been reported in Ituri province, with a small number in North Kivu and South Kivu. The WHO is scaling up diagnostic capacities and strengthening the laboratory network to deliver real-time data.

Uganda has ordered a temporary closure of its border with Congo, with mandatory 21-day isolation for anyone entering from Congo under emergency circumstances. Congo’s health ministry reported 101 confirmed cases and more than 3,000 possible contacts.

The U.S. administration is reportedly planning to send Americans exposed to Ebola to a new facility in Kenya, a move described by health law experts as “unprecedented”. An American doctor working in Congo tested positive and is receiving treatment in Berlin.