The Democratic Republic of Congo's Ebola outbreak has surpassed 4,000 confirmed cases for the first time, underscoring the scale of the country's worst-ever epidemic and one of the deadliest public health emergencies in recent history.
Government data released Thursday showed 4,053 confirmed infections and 1,850 deaths since the outbreak was officially declared on May 15.
Health authorities also reported about 793 recoveries, while nearly 700 patients remained hospitalized or in isolation as response teams continued battling the virus.
The epidemic has become the world's second-largest Ebola outbreak on record and the largest ever recorded in Congo, where the virus was first identified in 1976. It has also been described by health experts as the fastest-spreading Ebola outbreak ever documented.
Only the devastating 2014-16 West African epidemic, which infected more than 28,000 people across Guinea, Liberia and Sierra Leone, has recorded a higher number of cases.
Scientists believe the outbreak had been spreading for months before it was officially detected.
A study published last month in the journal Science concluded transmission likely began in January, or even earlier, near the gold-mining town of Mongbwalu in Ituri province. Researchers identified more than 500 suspected cases before authorities declared the outbreak in mid-May.
The delayed detection gave the virus a significant head start, allowing it to spread through communities before large-scale containment measures could be launched.
The outbreak is caused by the Bundibugyo strain of the Ebola virus, a rare species for which there is currently no licensed vaccine or approved treatment.
While vaccines and therapies developed for the more common Zaire strain are being used in some areas under expanded access or clinical studies, health officials continue racing to evaluate experimental vaccines and treatments specifically targeting Bundibugyo.
The disease has now spread across five provinces: Ituri, North Kivu, South Kivu, Haut-Uele and Tshopo. Ituri remains the epicenter, accounting for the overwhelming majority of infections, with more than 50 health zones affected nationwide.
Health experts say the outbreak has been fueled by a combination of delayed surveillance, ongoing armed conflict in eastern Congo, large-scale population displacement, extensive movement linked to artisanal gold mining and persistent mistrust of health authorities.
Together, those factors have complicated contact tracing, isolation efforts and safe burial practices, allowing the virus to spread faster than response teams can contain it.
Many patients have died before reaching treatment centers, increasing the risk of community transmission.
Children have also been among the hardest hit, with aid agencies reporting high fatality rates among younger patients.
Neighboring Uganda detected a limited number of linked infections but successfully halted local transmission through rapid containment measures before declaring its outbreak over. Nevertheless, regional health agencies continue to warn that surrounding countries remain at high risk because of frequent cross-border movement.
International health organizations, including the World Health Organization, Africa CDC and Medecins Sans Frontieres, continue supporting Congo's response, but officials say major obstacles remain. Security threats, attacks on health facilities, shortages of isolation beds and medical supplies, funding gaps and incomplete contact tracing continue to hamper efforts to slow transmission.
Experts also caution that the true scale of the outbreak is almost certainly larger than official figures suggest. Limited laboratory capacity in remote areas, underreporting and deaths outside the formal health system mean many infections likely remain undetected.