The Ebola epidemic in Democratic Republic of Congo is on track to surpass 4,000 cases this week and has been described as the fastest spreading on record since it was officially declared in May.
It is already the world's second-largest epidemic after West Africa's 2014-16 outbreak in Guinea, Liberia and Sierra Leone, when the World Health Organization recorded more than 28,000 cases and 11,000 deaths.
Delayed detection, overwhelmed surveillance, military conflict and a lack of vaccines and treatments for the species of the virus involved have allowed the disease to outrun containment efforts this time.
How fast is it spreading?
Health officials say the current epidemic is spreading five times faster than previous outbreaks did at this stage.
A 2018-2020 outbreak in Congo was previously the largest on record in the country, ending with 3,481 cases and 2,299 deaths recorded over two years. It took more than 10 months for eastern Congo to surpass 2,000 confirmed cases in that outbreak.
The current epidemic reached that figure in roughly two months and by late July had become the largest Ebola epidemic ever recorded in the country, less than three months after it was officially declared.
A headstart for the virus
The rare Bundibugyo species of the virus spread undetected for months before the outbreak was declared in May.
Reuters reported that early cases were missed, some being diagnosed as peritonitis. Local funeral practices helped the virus spread before any alarm was raised, and continue to undermine the response.
Later, health workers initially relied on tests for the wrong species of Ebola and samples sent to Kinshasa were mishandled, allowing the virus to spread undetected for months and making it difficult to regain control.
A July report published in Science, a peer-reviewed academic journal, concluded that the outbreak had begun at least as early as January on the outskirts of the mining town of Mongbwalu.
Surveillance teams unable to catch up
World Health Organization officials estimated in July that around 80% of new infections emerged outside known transmission chains, suggesting most cases are identified only after the virus has spread rapidly through communities.
A Reuters visit with stretched surveillance teams in Ituri Province found contact tracers lack resources and are overwhelmed by case loads while investigating alerts and monitoring contacts.
Health officials say the result is a vicious cycle: undetected transmission creates more cases, which further stretches already overburdened surveillance teams.
Aid cuts and unpaid salaries
Aid cuts have affected both surveillance efforts that might have caught the disease earlier and the ongoing effort to contain it.
USAID was awarding a five-year contract in 2025 to carry out health surveillance in Congo when the agency was abruptly shuttered last year, Tom Van Boven, the global health security team lead, told Reuters.
Reuters reported in June that key parts of the Ebola response were facing funding and staffing shortfalls.
As of mid-July, WHO had received less than half the funding needed to fight the eastern Congo outbreak. Health workers have also protested over unpaid salaries.
Those challenges have been compounded by broader cuts to humanitarian assistance such as programs to provide water and sanitation, to which the U.S. was also the top donor.
No vaccine, no proven treatment
Unlike the more common Zaire species behind the 2018-2020 outbreak, for which vaccines and treatments exist, there is no licensed vaccine or proven treatment for the Bundibugyo species driving this epidemic.
One infectious disease expert noted that most vaccines developed over the past decade focused on the Zaire species, leaving responders with fewer powerful tools this time.
The outbreak is concentrated in eastern Congo, a region affected by violence for decades, where conflict has delayed access to communities, disrupted the movement of personnel and supplies, and complicated contact tracing.
Eastern Congo sits along major trade and migration routes, with people travelling between towns, displacement camps and neighbouring countries.
Reuters reported in June on dozens of suspected Ebola-linked deaths at a displacement camp, raising concerns about transmission among hard-to-monitor, mobile populations.
