Democratic Republic of the Congo's worst Ebola crisis in history has now claimed more than 1,700 lives, with researchers racing to test experimental treatments against a strain of the virus that has no approved countermeasures. The outbreak, driven by the rare Bundibugyo variant, has infected nearly 4,000 people since May, making it the second-largest Ebola epidemic ever recorded and the fastest-spreading one on record. Main Developments Government figures show 1,707 people have died out of 3,802 confirmed cases since the outbreak was declared on May 15. The epicenter remains the eastern province of Ituri, which accounts for nearly 90 percent of all reported infections, though cases have also emerged in five other provinces, including the major city of Kisangani. Read also: Wenger says he was unaware of FIFA's $20bn investor plan Health authorities are currently tracking more than 17,000 contacts of infected individuals, with around 80 percent of those being followed up daily, according to WHO data. The response has also been complicated by the fact that more than 100 healthcare workers have contracted the virus since the crisis began. Vasee Moorthy, acting head of the WHO's R&D Blueprint programme, told reporters in Geneva that years of advance planning have enabled researchers to launch trials of experimental treatments and vaccines far sooner than in previous outbreaks. He cautioned, however, that only clinical trials will reveal whether these investigational products actually work. Background The Bundibugyo strain differs fundamentally from the Zaire strain that drove the 2014-2016 West Africa epidemic, which infected roughly 28,000 people and killed more than 11,000. That outbreak took about eight months to reach 1,000 deaths, underscoring how unusually rapid the current spread has been. Unlike other Ebola variants, no approved vaccines or treatments exist for Bundibugyo, leaving health workers reliant on experimental options. The response has been further hampered by delays in contact tracing, violence from armed groups, attacks on health facilities, difficult terrain, and widespread community mistrust of health authorities. Funding shortfalls following recent cuts to aid budgets have added to the strain. Front-line workers in the hard-hit town of Mongbwalu threatened on Monday to escalate industrial action unless overdue wages were paid within 24 hours, while staff in Bunia have previously staged strikes over unpaid salaries and dangerous working conditions. Why It Matters This outbreak is now the fastest-growing Ebola epidemic on record, and its speed poses a serious challenge to containment efforts. The concentration of cases in Ituri, a region already destabilized by armed conflict, raises the risk that the virus could spread further across borders. Neighboring Uganda declared itself Ebola-free in mid-June after its last patient was discharged, but the continued presence of cases in five other Congolese provinces shows the geographic reach of the crisis. The lack of approved countermeasures for the Bundibugyo strain means the world is watching these trials as a potential blueprint for responding to future rare-variant outbreaks. What's Next WHO Director-General Tedros Adhanom Ghebreyesus is scheduled to arrive in the Congolese capital Kinshasa on Tuesday before traveling later this week to Bunia, near the outbreak's center. Africa Centres for Disease Control and Prevention Director-General Jean Kaseya, making his second visit to the region, said it remains unclear when the outbreak will reach its peak. Clinical trial results for the experimental medicines and vaccines are expected to determine their effectiveness, though Moorthy emphasized that promising preclinical data must be confirmed in human studies. Whether the industrial action in Mongbwalu escalates and how quickly funding gaps are addressed will also shape the trajectory of the response in the coming weeks.