Congo's public health institute on Sunday said in its latest report that confirmed cases had risen to 4945, including 101 new cases detected in the previous 24 hours.
The outbreak, Congo's 17th, was already the biggest in the country's history in terms of number of cases - a milestone reached in late July.
The latest government data shows the total number of deaths has surpassed the 2299 deaths recorded in Congo's 2018-2020 outbreak, which was previously the country's worst on record.
There are now 4945 confirmed cases, the data showed.
Three months after it was formally announced, the outbreak is now dwarfed only by West Africa's 2014-2016 outbreak in which 28,616 cases and 11,310 deaths were recorded across Guinea, Liberia and Sierra Leone, according to the World Health Organisation.
It took nearly five months from the declaration of that outbreak to hit 1000 deaths, whereas Congo's current outbreak hit 2000 deaths in less than three months.
The current outbreak is caused by the Bundibugyo species of Ebola, which has no approved vaccines or treatments. TIt has gained momentum since it was declared on May 15, as weak health infrastructure, community resistance and instability hinder the effort to identify and respond to cases.
The proportion of people dying from the outbreak after a confirmed infection, known as the case fatality ratio, has risen from about 20 per cent in early June to 46 per cent, according to government data, meaning nearly one in every two confirmed cases is now fatal.
Experts say the trend does not indicate the virus has become more lethal. Instead, it points to persistent shortcomings in surveillance, case detection and access to care.
"Normally, as an outbreak progresses, the case fatality ratio should fall as contact tracing improves and patients are identified and treated earlier," said Thomas Parisch, a public health specialist recently deployed to Democratic Republic of Congo with Medecins Sans Frontieres.
"Instead, we're still seeing many cases detected very late, when treatment is less likely to succeed, with many identified only after they die in the community."
A small number of experimental vaccines and therapies are being evaluated, while global health authorities assess whether existing Ebola treatments could offer protection.
Evidence so far is limited to animal studies. The outbreak earlier spread to neighbouring Uganda, but authorities there managed to limit deaths to two and confirmed cases to 20 before declaring an end to the outbreak in that country in July.
Ebola spreads through direct contact with the bodily fluids of infected people, living or dead. It can cause fever, vomiting, diarrhoea and, in severe cases, internal and external bleeding.
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