The World Health Organization has announced clinical trials of two antiviral treatments for Ebola in the Democratic Republic of Congo, as the number of confirmed cases surpasses 1,000 in what has become one of the fastest-spreading outbreaks on record. The trials, set to begin next week, will test whether the two drugs — donated in part by the United States and pharmaceutical company Gilead Sciences — can reduce mortality in patients infected with the Bundibugyo strain of the virus, both individually and in combination.

The Bundibugyo strain, named after the town in western Uganda where it was first identified nearly two decades ago, has no approved treatment or vaccine. Between 500 and 1,000 patients are expected to participate in the trials, which will begin at a hospital in Ituri, a province in DR Congo's north-east where the vast majority of cases have been detected. The trial will be conducted by a consortium including DR Congo's National Institute for Biomedical Research, the medical humanitarian organisation ALIMA, Oxford University, and WHO. "WHO and our partners are working closely with the communities to inform and involve them in the trial," said WHO Director-General Tedros Adhanom Ghebreyesus.

The outbreak, declared on 15 May, has now recorded 1,048 confirmed cases and at least 267 deaths, with the true toll believed to be higher. Health officials say it was detected relatively late, in a remote area of eastern Congo, allowing the virus to spread before containment measures could be put in place. According to WHO, no previous Ebola outbreak had recorded so many infections in its first month. The response has also been hampered by deep community mistrust: health workers have faced threats, and hospitals treating Ebola patients have been stormed by angry crowds.

The outbreak has now crossed borders. A French doctor who had been working in eastern Congo for ALIMA tested positive for Ebola upon returning to France, prompting authorities to place five fellow passengers from an Air France flight from Kinshasa's main airport into precautionary isolation for 21 days. The doctor, whose condition is described as stable, reportedly began experiencing worsening headaches during the flight and alerted authorities on landing at Paris-Charles de Gaulle. Tedros has sought to limit alarm, noting that fewer than 30 Ebola infections have been recorded outside Africa in the past 50 years, and that the risk to other European countries remains low.

Why this matters: the scale and speed of this outbreak, combined with the absence of any approved treatment or vaccine for the Bundibugyo strain, makes the upcoming trials critically important. A successful therapy could not only save lives in the current crisis but also build long-term preparedness for a strain that has so far remained largely outside the focus of global pharmaceutical research. Meanwhile, the case in France serves as a reminder of how quickly a localised outbreak can reach distant countries — and of the risks faced by the aid workers responding on the front lines.